Organic EL display panel and method of manufacturing organic EL display panel

ABSTRACT

An organic EL display panel includes a substrate, a plurality of pixel electrodes disposed in a matrix pattern over the substrate, a first current feeding auxiliary electrode layer disposed to extend in a column or row direction in at least one of gaps between adjacent ones of the pixel electrodes over the substrate, a second current feeding auxiliary electrode layer that contains aluminum as a main constituent and is disposed to be superposed on the first current feeding auxiliary electrode layer, a plurality of light emitting layers disposed on the plurality of pixel electrodes, and a common electrode layer disposed continuously to cover the first current feeding auxiliary electrode layer and the second current feeding auxiliary electrode layer as well as an upper side of the plurality of light emitting layers.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/945,655, filed on Apr. 4, 2018, which claims priority toJapanese Patent Application No. 2017-075156 filed Apr. 5, 2017, JapanesePatent Application No. 2017-128990 filed Jun. 30, 2017 and JapanesePatent Application No. 2017-132646 filed Jul. 6, 2017. The contents ofthese applications are incorporated herein by reference in theirentirety.

BACKGROUND

The present disclosure relates to an organic EL (Electro Luminescence)display panel which uses organic EL elements utilizing anelectroluminescence phenomenon of organic materials, and to a method ofmanufacturing the same.

In recent years, as a display panel for use in a display device such asa digital television set, an organic EL display panel having a pluralityof organic EL elements arranged in a matrix pattern on a substrate hasbeen put to practical use.

In an organic EL display panel, in general, a light emitting layer ofeach organic EL element and the adjacent organic EL element arepartitioned from each other by an insulating layer formed from aninsulating material. In an organic EL display panel for color display,organic EL elements form sub-pixels that emit light in R, G and Bcolors, individually, and the R, G and B sub-pixels adjacent to oneanother are combined to form a unit pixel in color display.

The organic EL element has a basic structure in which a light emittinglayer containing an organic light emitting material is disposed betweena pair of electrodes. At the time of driving, a voltage is impressedbetween the pair of electrodes, and light is emitted attendant onrecombination of holes and electrons injected into the light emittinglayer.

An organic EL element of the top emission type has an element structurein which a pixel electrode, organic layers (inclusive of a lightemitting layer) and a common electrode are sequentially provided over asubstrate. Light from the light emitting layer is reflected by the pixelelectrode formed from a light reflecting material, and is emitted upwardfrom the common electrode formed from a light transmitting material. Thecommon electrode is often formed over the whole surface of a displaypixel section on the substrate. Attendant on an increase in the size oforganic EL display panels for use in larger-sized display devices suchas television sets, the electric resistance of the common electrode isincreased. At parts far from a current feeding part, therefore,sufficient current supply is not attained, due to a voltage drop, andlight emission efficiency is thereby lowered. This may lead togeneration of irregularities in luminance

In view of this problem, for example, Japanese Patent Laid-open No.2002-318556 proposes a technique for lowering the electric resistance ofthe common electrode. In the technique, an auxiliary electrode layer isextended in the same layer as pixel electrodes on a substrate, and acommon electrode is superposed thereon, for achieving electricalconnection with the common electrode. In addition, there have beenproposed a technique in which an auxiliary electrode layer and a commonelectrode are stacked on each other through a hole injection layerformed from a metallic oxide in order to achieve electrical connectionbetween the auxiliary electrode layer and the common electrode (see, forexample, Japanese Patent No. 5884224), and a technique in which stackingof the layers is conducted through an electron transport layercontaining metallic atoms (see, for example, WO 2015/151415).

SUMMARY

According to an embodiment of the present disclosure, there is providedan organic EL display panel having a plurality of pixel electrodesarranged in a matrix pattern on a substrate, with a light emitting layerdisposed on each of the pixel electrodes, the light emitting layercontaining an organic light emitting material, the organic EL displaypanel including: the substrate; the plurality of pixel electrodesdisposed in a matrix pattern over the substrate; a first current feedingauxiliary electrode layer disposed to extend in a column or rowdirection in at least one of gaps between adjacent ones of the pixelelectrodes over the substrate; a second current feeding auxiliaryelectrode layer that contains aluminum as a main constituent and isdisposed to be superposed on the first current feeding auxiliaryelectrode layer; a plurality of light emitting layers disposed on theplurality of pixel electrodes; and a common electrode layer disposedcontinuously to cover the first current feeding auxiliary electrodelayer and the second current feeding auxiliary electrode layer as wellas an upper side of the plurality of light emitting layers, in which thefirst current feeding auxiliary electrode layer and the common electrodelayer make contact with each other at least in a partial area on a wallsurface perpendicular to an upper surface of the first current feedingauxiliary electrode layer, the second current feeding auxiliaryelectrode layer contains aluminum as a main constituent, with an oxideof aluminum being formed at least at a surface layer of the secondcurrent feeding auxiliary electrode layer, and the first current feedingauxiliary electrode layer is composed of a material that contains ametal different from aluminum as a main constituent and is lower thanaluminum in contact resistance in air.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, advantages, and features of the technologypertaining to the present disclosure will become apparent from thefollowing description thereof taken in conjunction with the accompanyingdrawings, which illustrate at least one embodiment of the technologypertaining to the present disclosure.

FIG. 1 is a schematic block diagram of a circuit configuration of anorganic EL display device according to Embodiment 1;

FIG. 2 is a schematic circuit diagram of each sub-pixel in an organic ELdisplay panel used in the organic EL display device according toEmbodiment 1;

FIG. 3 is a schematic plan view depicting a part of the organic ELdisplay panel according to at least one embodiment;

FIG. 4 is a schematic sectional view taken along line A1-A1 of FIG. 3,according to at least one embodiment;

FIG. 5 is a sectional view of the vicinity of a second auxiliaryelectrode layer depicted in FIG. 4, according to at least oneembodiment;

FIGS. 6A to 6D are schematic sectional views taken at the same positionas line A1-A1 of FIG. 3 in a state of each step in manufacture of theorganic EL display panel according to at least one embodiment;

FIGS. 7A to 7C are schematic sectional views taken at the same positionas line A1-A1 of FIG. 3 in a state of each step in manufacture of theorganic EL display panel according to at least one embodiment;

FIGS. 8A to 8D are schematic sectional views taken at the same positionas line A1-A1 of FIG. 3 in a state of each step in manufacture of theorganic EL display panel according to at least one embodiment;

FIGS. 9A to 9G are schematic sectional views taken at the same positionas line A1-A1 of FIG. 3 in a state of each step in manufacture of theorganic EL display panel according to at least one embodiment;

FIGS. 10A and 10B are schematic sectional views taken at the sameposition as line A1-A1 of FIG. 3 in a state of each step in manufactureof the organic EL display panel according to at least one embodiment;

FIG. 11 is a schematic view of a sputtering system used for producing acommon electrode layer according to at least one embodiment;

FIG. 12A is a schematic plan view of a bank and an auxiliary electrodelayer in a display panel according to Modification 1, FIG. 12B is aschematic plan view of a bank and an auxiliary electrode layer in adisplay panel according to Modification 2, and FIG. 12C is a schematicplan view of a bank and an auxiliary electrode layer in a display panelaccording to Modification 3;

FIG. 13A is a schematic sectional view taken along line A3-A3 of FIG.12A, and

FIG. 13B is a schematic sectional view taken along line A4-A4 of FIG.12B according to at least one embodiment;

FIG. 14A is a sectional view of the vicinity of a second auxiliaryelectrode layer in a display panel according to Modification 4, and FIG.14B is a sectional view of Modification 4A in which a second auxiliaryelectrode layer and a hole injection layer are not provided on a firstauxiliary electrode layer in the display panel;

FIG. 15A is a sectional view of the vicinity of a second auxiliaryelectrode layer in a display panel according to Modification 5, and FIG.15B is a sectional view of Modification 5A in which a second auxiliaryelectrode layer and a hole injection layer are not provided on a firstauxiliary electrode layer in the display panel;

FIG. 16A is a sectional view of the vicinity of a second auxiliaryelectrode layer in a display panel according to Modification 6, and FIG.16B is a sectional view of Modification 6A in which a second auxiliaryelectrode layer and a hole injection layer are not provided on a firstauxiliary electrode layer in the display panel;

FIG. 17 is a schematic plan view of a part of the organic EL displaypanel according to at least one embodiment;

FIG. 18 is a schematic sectional view taken along line A1-A1 of FIG. 17;

FIG. 19 is an enlarged view of the vicinity of the second auxiliaryelectrode layer depicted in FIG. 18;

FIGS. 20A and 20B are schematic sectional views taken along line A1-A1of FIG. 17 in each step in manufacture of the organic EL display panelaccording to at least one embodiment, and FIGS. 20C and 20D areschematic sectional views taken along line A2-A2 of FIG. 17 in each stepin manufacture of the organic EL display panel according to at least oneembodiment;

FIGS. 21A to 21D are schematic sectional views taken alone line A1-A1 ofFIG. 17 in each step in manufacture of the organic EL display panelaccording to at least one embodiment;

FIGS. 22A to 22D are schematic sectional views taken along line A1-A1 ofFIG. 17 in each step in manufacture of the organic EL display panelaccording to at least one embodiment;

FIGS. 23A to 23G are schematic sectional views taken long line A1-A1 ofFIG. 17 in each step in manufacture of the organic EL display panelaccording to at least one embodiment;

FIGS. 24A and 24B are schematic sectional views taken along line A1-A1of FIG. 17 in each step in manufacture of the organic EL display panelaccording to at least one embodiment;

FIG. 25 is a schematic diagram of a circuit configuration of the displaypanel according to at least one embodiment;

FIG. 26 is a schematic view of a sectional configuration of the displaypanel according to at least one embodiment;

FIG. 27 is a schematic view of a sectional configuration of the displaypanel according to at least one embodiment;

FIGS. 28A to 28E are schematic views depicting manufacturing steps ofthe display panel according to at least one embodiment;

FIGS. 29A to 29E are schematic views depicting manufacturing steps ofthe display panel according to at least one embodiment;

FIG. 30 is a schematic view of a sectional configuration of the displaypanel according to at least one embodiment;

FIG. 31 is a schematic view of a sectional configuration of the displaypanel according to at least one embodiment;

FIG. 32 is a schematic diagram depicting a manufacturing step of thedisplay panel according to at least one embodiment;

FIG. 33 is a schematic view of a sectional configuration of the displaypanel according to at least one embodiment;

FIG. 34 is a schematic diagram depicting a manufacturing step of thedisplay panel according to at least one embodiment;

FIG. 35 is a schematic view of a sectional configuration of the displaypanel according to at least one embodiment;

FIG. 36 is a schematic view of a sectional configuration of the displaypanel according to at least one embodiment;

FIGS. 37A to 37G are schematic views depicting manufacturing steps ofthe display panel according to at least one embodiment;

FIG. 38 is a schematic view of a sectional configuration of the displaypanel according to at least one embodiment; and

FIG. 39 is a schematic view of a sectional configuration of the displaypanel according to at least one embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1

<How Embodiment 1 of the Present Disclosure has Been Reached>

However, in the case where a metal having a light reflecting propertylike the pixel electrodes, such as aluminum or silver, is used as thematerial for the auxiliary electrode layer, there has been a problemthat an oxide film is formed at a surface layer of the auxiliaryelectrode layer in the subsequent manufacturing step, whereby electriccontact resistance between the auxiliary electrode layer and the commonelectrode layer is raised.

Thus, there is a need for an organic EL display panel and a method ofmanufacturing the same in which while using an inexpensive metallicmaterial having a light reflecting property like pixel electrodes isused as the material for an auxiliary electrode layer, electric contactresistance in electrical connection between a common electrode layer andthe auxiliary electrode layer can be reduced, light emission efficiencycan be enhanced, and variability in luminance can be restrained.

How an embodiment of the present disclosure has been reached will now bedescribed below.

In a top emission type organic EL element, an optical resonatorstructure is adopted by setting optimum thicknesses of layers, wherebychromaticity of light emitted is controlled and luminance is enhanced.Therefore, a surface portion of each pixel electrode should be high inlight reflecting property. Accordingly, a metal layer, an alloy layer, atransparent conductive film layer or the like is selected for the pixelelectrodes. The metal layer can be formed from a metallic material whichis low in sheet resistance and high in light reflecting property, suchas silver (Ag) or aluminum (Al). Taking materials cost intoconsideration, it is industrially preferable to use aluminum rather thansilver.

On the other hand, a current feeding auxiliary electrode layer is formedsimultaneously with, and in the same layer as, the pixel electrodes on asubstrate. Therefore, the current feeding auxiliary electrode layer isformed from the same material as the pixel electrodes. Accordingly, ametal layer or an alloy layer containing aluminum as a main constituentis used for the auxiliary electrode layer. In this case, however, it hasbeen found by the present inventors' investigation that in the processof producing upper layers after the formation of the auxiliary electrodelayer, an oxide film is formed at a surface layer of the auxiliaryelectrode layer, whereby the electric contact resistance between theauxiliary electrode layer and the common electrode layer is enhanced.The reason for this is considered to lie in that the metal layer oralloy layer containing aluminum as a main constituent and constitutingthe auxiliary electrode layer is oxidized in a baking step or a wetprocess or the like for a hole injection layer and banks which areformed after the formation of the auxiliary electrode layer.

Particularly, it has been found by the present inventors' investigationthat not only the electric contact resistance between the auxiliaryelectrode layer and the common electrode is increased by theintermediate presence of the hole injection layer but also the aluminumalloy of the auxiliary electrode layer becomes susceptible to oxidation,in the case where electrical connection between the auxiliary electrodelayer and the common electrode is contrived by stacking the auxiliaryelectrode layer and the common electrode through the intermediatepresence of the hole injection layer formed of a metallic oxide (forexample, tungsten oxide: WOx), as described in Japanese Patent No.5884224. In addition, it has been found by the present inventors'experiments that even in the case where an aluminum alloy, which isgenerally reported to indicate good electric contact resistance incontact with ITO, is used as the material for the auxiliary electrodelayer, an aluminum oxide film is formed at the surface of the auxiliaryelectrode, increasing the electric contact resistance between theauxiliary electrode and the common electrode. The reason for this isconsidered to reside in that oxygen contained in tungsten oxide itselfis liable to migrate into the auxiliary electrode layer, or, because oftungsten oxide having higher pore density than other materials, that achemical liquid such as a developing liquid and/or water may penetrateinto the auxiliary electrode layer from upper layers in the wet processor baking step, or that passage of oxygen at the time of baking leads toeasy penetration of oxygen into the auxiliary electrode layer.

It has been also found that in the case where an aluminum alloy of theauxiliary electrode layer is oxidized and where electrical connectionbetween the auxiliary electrode layer and the common electrode islocally made without intermediate presence of the oxide filmtherebetween due to the presence of a defect or foreign matter in theauxiliary electrode layer, there is a possibility that concentrated flowof current may occur in the local site, causing local heat generation ormaterial deterioration or the like.

Furthermore, for increasing carrier mobility at a light emitting elementpart, a configuration in which an auxiliary electrode layer and a commonelectrode are stacked through an electron transport layer containing ahigh-resistance fluoride and metallic atoms has been proposed, asdescribed in WO 2015/151415. However, since the electric polaritybetween the auxiliary electrode layer and the common electrode isopposite to that between the pixel electrode and the common electrode,the intermediate presence of the electron transport layer which containsthe high-resistance fluoride and the metallic atoms but is not a metallayer per se would lead to a further increase in electric contactresistance between the auxiliary electrode layer and the commonelectrode. For further enhancement of carrier mobility, an increase infilm thickness of the electron transport layer should also be taken intoconsideration.

On the other hand, Japanese Patent Laid-open No. 2009-283304 proposes anorganic EL element having a light emission functional layer interposedbetween an auxiliary electrode layer and a counter electrode, in whichthe auxiliary electrode layer makes contact with the counter electrodewithout intermediate presence therebetween of an electron transportlayer, at a side surface, as viewed in sectional view. In thisconfiguration, however, electric contact resistance between theauxiliary electrode layer and the counter electrode is raised in thecase where an oxide film is formed at a surface layer of the auxiliaryelectrode layer, as aforementioned.

In view of the foregoing, the present inventors made extensive andintensive investigations in regard of a configuration in which aninexpensive metallic material having a light reflecting property likethe material of pixel electrodes is used as the material for anauxiliary electrode layer and in which electric contact resistancebetween a common electrode layer and the auxiliary electrode layer canbe lowered. As a result of their investigations, they have reached thefollowing embodiments.

<Outline of Embodiment 1 of the Present Disclosure>

An organic EL display panel according to a mode of the presentdisclosure is an organic EL display panel having a plurality of pixelelectrodes arranged in a matrix pattern on a substrate, with a lightemitting layer disposed on each of the pixel electrodes, the lightemitting layer containing an organic light emitting material, theorganic EL display panel including: the substrate; the plurality ofpixel electrodes disposed in a matrix pattern over the substrate; afirst current feeding auxiliary electrode layer disposed to extend in acolumn or row direction in at least one of gaps between adjacent ones ofthe pixel electrodes over the substrate; a second current feedingauxiliary electrode layer that contains aluminum as a main constituentand is disposed to be superposed on the first current feeding auxiliaryelectrode layer; a plurality of light emitting layers disposed on theplurality of pixel electrodes; and a common electrode layer disposedcontinuously to cover the first current feeding auxiliary electrodelayer and the second current feeding auxiliary electrode layer as wellas an upper side of the plurality of light emitting layers, in which thefirst current feeding auxiliary electrode layer and the common electrodelayer make contact with each other at least in a partial area on a wallsurface perpendicular to an upper surface of the first current feedingauxiliary electrode layer, and the first current feeding auxiliaryelectrode layer is composed of a material that contains a metaldifferent from aluminum as a main constituent and is lower than aluminumin contact resistance in air.

In another mode, in the above configuration, an oxide of aluminum may beformed at least at a surface layer of the second current feedingauxiliary electrode layer.

According to such a configuration, electric contact resistance inelectrical connection between the common electrode layer and theauxiliary electrode layer can be reduced even in the case where aninexpensive metallic material having a light reflecting property likethe material of the pixel electrodes is used as a material for theauxiliary electrode layer. As a result, light emission efficiency can beenhanced, and variability in luminance can be restrained.

In another mode, in any of the above modes, a configuration may beadopted in which a functional layer composed of at least one layerdisposed continuously to cover the first current feeding auxiliaryelectrode layer and the second current feeding auxiliary electrode layeras well as an upper side of the plurality of light emitting layers isfurther provided between the second current feeding auxiliary electrodelayer and the common electrode layer, the functional layer is lacking orthinned in a vicinity of a partial area of the first current feedingauxiliary electrode layer, and the thickness of the first currentfeeding auxiliary electrode layer is greater than the thickness of thefunctional layer on the light emitting layer.

According to such a configuration, it is ensured that even in the casewhere the auxiliary electrode layer and the common electrode are stackedthrough a hole injection layer composed of a metallic oxide (WOx) or thecase where the auxiliary electrode layer and the common electrode arestacked through an electron transport layer containing metallic atomsfor the purpose of increasing carrier mobility at a light emittingelement part, the first current feeding auxiliary electrode layer andthe common electrode layer can be made to contact each other at least ata partial area on the wall surface perpendicular to the upper surface ofthe first current feeding auxiliary electrode layer.

In another mode, in any of the above modes, the resistance in a vicinityof a surface layer of the second current feeding auxiliary electrodelayer may be higher than the resistance in a vicinity of a surface layerof the first current feeding auxiliary electrode layer. In another mode,in any of the above modes, the contact resistance between the firstcurrent feeding auxiliary electrode layer and the common electrode layermay be lower than the contact resistance between the second currentfeeding auxiliary electrode layer and the common electrode layer. Inanother mode, in any of the above modes, the sheet resistance of thematerial may be higher than the sheet resistance of aluminum.

In another mode, in any of the above modes, the metal different fromaluminum may be at least one metal selected from among tungsten,chromium, titanium, molybdenum, nickel, copper, lanthanum, and indium,or a stacked layer of metals including them.

According to such a configuration, it is ensured that since these metalsare chemically stable at room temperature, an oxide of metal is lessliable to be formed at a surface layer part of the first auxiliaryelectrode layer as compared to the case of aluminum.

In another mode, in any of the above modes, the first current feedingauxiliary electrode layer may be composed of ITO or IZO.

According to such a configuration, it is ensured that since these oxidesare chemically stable at room temperature, an oxide of metal is lessliable to be formed at a surface layer part of the first current feedingauxiliary electrode layer. Alternatively, notwithstanding ITO, IZO orthe like is an oxide per se, a configuration with conductivity can berealized. Therefore, a contact resistance in air which is lower thanthat of aluminum is realized. In other words, a configuration in whichthe resistance in the vicinity of a surface layer of the second currentfeeding auxiliary electrode layer is higher than the resistance in thevicinity of a surface layer of the first current feeding auxiliaryelectrode layer can be realized.

In another mode, in any of the above modes, a configuration may beadopted in which when the functional layer is referred to as a firstfunctional layer, a second functional layer disposed discontinuouslyunder the plurality of light emitting layers and over the first currentfeeding auxiliary electrode layer and the second current feedingauxiliary electrode layer is further provided between the second currentfeeding auxiliary electrode layer and the first functional layer.

According to such a configuration, the auxiliary electrode layer and thecommon electrode can be stacked through a hole injection layer composedof a metallic oxide (WOx).

In another mode, in any of the above modes, a transparent conductivelayer composed of ITO or IZO and disposed discontinuously under theplurality of light emitting layers and over the first current feedingauxiliary electrode layer and the second current feeding auxiliaryelectrode layer is further provided between the second current feedingauxiliary electrode layer and the functional layer.

According to such a configuration, the transparent conductive layer canbe utilized as an optical adjustment layer for securing an opticallength required for an optical resonator structure between the pixelelectrodes and the common electrode.

In another mode, in any of the above modes, the common electrode layermay include a transparent conductive layer composed of ITO or IZO.

According to such a configuration, the common electrode layer can beformed by a sputtering method, and the first current feeding auxiliaryelectrode layer and the common electrode layer can be made to contacteach other at least in a partial area on a wall surface perpendicular toan upper surface of the first current feeding auxiliary electrode layer.

In another mode, in any of the above modes, the common electrode layermay include a metal electrode layer containing silver as a mainconstituent.

According to such a configuration, the sheet resistance of the commonelectrode layer can be reduced.

In another mode, in any of the above modes, a configuration may beadopted in which a planarizing layer composed of a planarizing lowerlayer and a planarizing upper layer which contain a resin as a mainconstituent is provided over the substrate, a third current feedingauxiliary electrode layer is disposed to extend in a column or rowdirection between the planarizing lower layer and the planarizing upperlayer, the planarizing upper layer is formed therein with a contact holepenetrating to an upper surface of the third current feeding auxiliaryelectrode layer, with the first current feeding auxiliary electrodelayer being electrically connected to the third current feedingauxiliary electrode layer through the contact hole, the common electrodelayer is disposed to be continuous with an inner peripheral surface anda bottom surface of the contact hole, and the third current feedingauxiliary electrode layer and the common electrode layer areelectrically connected to each other through the first current feedingauxiliary electrode layer.

According to such a configuration, the sectional area of the auxiliaryelectrode can be increased by an amount corresponding to the section inthe row direction of the third current feeding auxiliary electrodelayer, the sheet resistance of the auxiliary electrode can be therebyreduced, and a lowering in light take-out efficiency attendant on anincrease in pixel density (increase in resolution) can be restrained. Inaddition, the configuration in which the auxiliary electrode is providedbetween the planarizing lower layer and the planarizing upper layer onthe substrate ensures that there is little positional limitation due topixel electrodes and the like on the substrate and that the degree offreedom in plan-view layout of the third current feeding auxiliaryelectrode layer is enhanced.

In another mode, a configuration may be adopted in which a functionallayer is further disposed between the bottom surface of the contact holeand the common electrode layer in the contact hole, the depth of thecontact hole is greater than the thickness of the functional layer, andthe first current feeding auxiliary electrode layer and the commonelectrode layer are in contact with each other at least in a partialarea on the inner peripheral surface of the contact hole in the firstcurrent feeding auxiliary electrode layer.

According to such a configuration, the area of contact between thecommon electrode layer and the first current feeding auxiliary electrodelayer can be increased, and the sectional area of a conducting path tothe third current feeding auxiliary electrode layer can be increased. Asa result, contact resistance from the common electrode layer to thecurrent feeding auxiliary electrode can be reduced. In another mode, inany of the above modes, a configuration may be adopted in which thesubstrate includes a TFT (Thin Film Transistor) substrate and aninsulating layer provided over the TFT substrate, the insulating layercontaining a resin as a main constituent, a planarizing layer containinga resin as a main constituent is provided over the substrate, a fourthcurrent feeding auxiliary electrode layer disposed to extend in a columnor row direction is provided between the TFT substrate and theinsulating layer, the planarizing layer is formed therein with a contacthole penetrating from an upper surface of the planarizing layer to alower surface of the fourth current feeding auxiliary electrode layer,with the first current feeding auxiliary electrode layer beingelectrically connected to the fourth current feeding auxiliary electrodelayer through the contact hole, the common electrode layer is disposedto be continuous with an inner peripheral surface and a bottom surfaceof the contact hole, and the fourth current feeding auxiliary electrodelayer and the common electrode layer are electrically connected to eachother through the first current feeding auxiliary electrode layer.

According to such a configuration, the sectional area of the auxiliaryelectrode can be increased by an amount corresponding to the section inthe row direction of the fourth current feeding auxiliary electrodelayer, the sheet resistance of the auxiliary electrode can be therebyreduced, and a lowering in light take-out efficiency attendant on anincrease in pixel density (increase in resolution) can be restrained. Inaddition, the configuration in which the auxiliary electrode is providedbetween a channel protection layer and an inorganic insulating layer inthe substrate ensures that there is little positional limitation due tothe pixel electrodes and the like on the substrate and that the degreeof freedom in plan-view layout of the fourth current feeding auxiliaryelectrode layer is enhanced.

In another mode, in any of the above modes, a configuration may beadopted in which a functional layer is further disposed between a bottomsurface of the contact hole in the substrate and the common electrodelayer in the contact hole, the depth of the contact hole is greater thanthe thickness of the functional layer, and the first current feedingauxiliary electrode layer and the common electrode layer are in contactwith each other at least in a partial area on the inner peripheralsurface of the contact hole in the first current feeding auxiliaryelectrode layer.

According to such a configuration, the area of contact between thecommon electrode layer and the first current feeding auxiliary electrodelayer can be increased, and the sectional area of a conducting path tothe fourth current feeding auxiliary electrode layer can be increased.As a result, the contact resistance from the common electrode layer tothe current feeding auxiliary electrode can be reduced.

In another mode, in any of the above modes, a configuration may beadopted in which the substrate includes a TFT substrate and aninsulating layer provided over the TFT substrate, the insulating layercontaining a resin as a main constituent, a planarizing layer composedof a planarizing lower layer and a planarizing upper layer which containa resin as a main constituent is provided over the substrate, a thirdcurrent feeding auxiliary electrode layer disposed to extend in a columnor row direction is provided between the planarizing lower layer and theplanarizing upper layer, a fourth current feeding auxiliary electrodelayer disposed to extend in the column or row direction is providedbetween the TFT substrate and the insulating layer, the planarizinglower layer, the planarizing upper layer and the insulating layer areformed therein with a contact hole which penetrates to an upper surfaceof the fourth current feeding auxiliary electrode layer, the firstcurrent feeding auxiliary electrode layer is electrically connected tothe third current feeding auxiliary electrode layer through the contacthole, the third current feeding auxiliary electrode layer iselectrically connected to the fourth current feeding auxiliary electrodelayer through the contact hole, the common electrode layer is disposedto be continuous with an inner peripheral surface and a bottom surfaceof the contact hole, and the third current feeding auxiliary electrodelayer and the fourth current feeding auxiliary electrode layer areelectrically connected to the common electrode layer through the firstcurrent feeding auxiliary electrode layer.

According to such a configuration, the common electrode layer and thethird current feeding auxiliary electrode layer are electricallyconnected, and, further, the fourth current feeding auxiliary electrodelayer is electrically connected, through the first current feedingauxiliary electrode layer. Therefore, the third current feedingauxiliary electrode layer and the fourth current feeding auxiliaryelectrode layer can be made to function as a current feeding auxiliaryelectrode for the common electrode layer. As a result, sheet resistancecan be further reduced, which is effective for realizing a higherresolution.

In another mode, in any of the above modes, a configuration may beadopted in which a functional layer is further disposed between a bottomsurface of the contact hole and the common electrode layer in thecontact hole, and the depth of the contact hole is greater than thethickness of the functional layer, and the first current feedingauxiliary electrode layer and the common electrode layer are in contactwith each other at least in a partial area on an inner peripheralsurface of the contact hole in the first current feeding auxiliaryelectrode layer.

According to such a configuration, the area of contact between thecommon electrode layer and the first current feeding auxiliary electrodelayer can be increased, the sectional area of a conducting path to thethird current feeding auxiliary electrode layer and the fourth currentfeeding auxiliary electrode layer can be thereby increased, and contactresistance from the common electrode layer to the current feedingauxiliary electrode can be reduced.

<Details of Embodiment 1>

1.1 Circuit Configuration of Display Device 1

A circuit configuration of an organic EL display device 1 (hereinafterreferred to as “display device 1”) according to Embodiment 1 will bedescribed below, referring to FIG. 1.

As illustrated in FIG. 1, the display device 1 includes an organic ELdisplay panel 10 (hereinafter referred to as “display panel 10”), and adrive control circuit section 20 connected thereto.

The display panel 10 is an organic EL (Electro Luminescence) panelutilizing an electroluminescence phenomenon of organic materials, inwhich a plurality of organic EL elements are arranged, for example, in amatrix pattern. The drive control circuit section 20 includes four drivecircuits 21 to 24 and a control circuit 25.

Note that in the display device 1, the layout of each circuit of thedrive control circuit section 20 in relation to the display panel 10 isnot limited to the one depicted in FIG. 1.

1.2 Circuit Configuration of Display Panel 10

In the display panel 10, a plurality of unit pixels 100 e are arrangedin a matrix pattern, to constitute a display region. Each unit pixel 100e is composed of three organic EL elements, namely, three sub-pixels 100se that emit light in R (red), G (green) and B (blue). A circuitconfiguration of each sub-pixel 100 se will be described referring toFIG. 2.

FIG. 2 is a circuit diagram depicting the circuit configuration in anorganic EL element 100 corresponding to each sub-pixel 100 se in thedisplay panel 10 used for the display device 1.

As depicted in FIG. 2, in the display panel 10 according to the presentembodiment, each sub-pixel 100 se includes two transistors Tr1 and Tr2,one capacitor C, and an organic EL element section EL as a lightemitting section. The transistor Tr1 is a drive transistor, whereas thetransistor Tr2 is a switching transistor.

A gate G2 of the switching transistor Tr2 is connected to a scan lineVscn, whereas a source S2 of the switching transistor Tr2 is connectedto a data line Vdat. A drain D2 of the switching transistor Tr2 isconnected to a gate G1 of the drive transistor Tr1.

A drain D1 of the drive transistor Tr1 is connected to a power supplyline Va, whereas a source Si of the drive transistor Tr1 is connected toa pixel electrode (anode) of the organic EL element section EL. A commonelectrode layer (cathode) in the organic EL element section EL isconnected to a ground line Vcat. In addition, a first auxiliaryelectrode layer 135 and a second auxiliary electrode layer 200, whichwill be described later, are also connected to the ground line Vcat, andthe common electrode layer, the first auxiliary electrode layer 135 andthe second auxiliary electrode layer 200 are interconnected.

Note that a first end of the capacitor C is connected to the drain D2 ofthe switching transistor Tr2 and the gate G1 of the drive transistorTr1, whereas a second end of the capacitor C is connected to the powersupply line Va.

In the display panel 10, a plurality of sub-pixels 100 se (for example,three sub-pixels 100 se that emit light in red (R), green (G) and blue(B)) adjacent to one another are combined to constitute a single unitpixel 100 e, and such unit pixels 100 e are arranged in a distributedmanner to constitute the pixel region. Besides, a gate line is led outfrom the gate G2 of each sub-pixel 100 se, and is connected to the scanline Vscn which is connected from the exterior of the display panel 10.Similarly, a source line is led out from the source S2 of each sub-pixel100 se, and is connected to the data line Vdat which is connected fromthe exterior of the display panel 10.

In addition, the power supply lines Va of the sub-pixels 100 se and theground lines Vcat of the sub-pixels 100 se are collectively connected toa power supply line and a ground line of the display device 1.

1.3 General Configuration of Display Panel 10

The display panel 10 according to the present embodiment will bedescribed referring to the drawings. Note that the drawings areschematic, and the magnification used therein may be different fromactual magnification.

FIG. 3 is a schematic plan view depicting a part of the display panelaccording to the embodiment.

The display panel 10 is an organic EL display panel utilizing anelectroluminescence phenomenon of organic materials, and has a topemission type configuration in which a plurality of organic EL elements100 arranged in a matrix pattern on a substrate 100 x (TFT substrate)formed with TFTs emit light through an upper surface. Herein, anX-direction, a Y-direction and a Z-direction in FIG. 3 are respectivelya row direction, a column direction and a thickness direction in thedisplay panel 10.

In a display region of the display panel 10, a plurality of unit pixels100 e composed of organic EL elements 100 are arranged in a matrixpattern. In each unit pixel 100 e, there are formed three kinds ofself-luminescence regions 100 a of 100aR which emits light in red, 100aGwhich emits light in green, and 100aB which emits light in blue (where100aR, 100aG and 100aB are not discriminated from one another, they willhereinafter be referred to simply as “100 a”) as regions for emittinglight by an organic compound. Specifically, three sub-pixels 100 se(where they are discriminated from one another, they will hereinafter bereferred to as “red sub-pixel 100seR,” “green sub-pixel 100seG” and“blue sub-pixel 100seB”) corresponding respectively to theself-luminescence regions 100aR, 100aG and 100aB arrayed in the rowdirection are combined into a set to constitute a unit pixel 100 e incolor display.

In the display panel 10, a plurality of auxiliary pixel electrodes 150(depicted in FIG. 4 to be described later) and a plurality of pixelelectrodes 119 are arranged on the substrate 100 x in the state of beingspaced at predetermined intervals in the row and column directions. Thepluralities of auxiliary pixel electrodes 150 and pixel electrodes 119are, for example, substantially rectangular in plan-view shape, and thepixel electrodes 119 are formed of a light reflecting material. Theauxiliary pixel electrodes 150 and pixel electrodes 119 arrayed orderlyin threes in the row direction correspond to the three self-luminescenceregions 100aR, 100aG and 100aB arrayed orderly in the row direction.

In addition, as depicted in FIGS. 3 and 4, in the display panel 10, aplurality of first current feeding auxiliary electrode layers 135(hereinafter referred to as “first auxiliary electrode layer 135”) aredisposed continuously over the column direction between the unit pixels100 e on the substrate 100 x. The first auxiliary electrode layers 135are formed of a light reflecting material different from that of thepixel electrodes 119. Besides, on the respective first auxiliaryelectrode layers 135, second current feeding auxiliary electrode layers200 (hereinafter referred to as “second auxiliary electrode layers 200”)are disposed continuously over the column direction between the unitpixels 100 e on the substrate 100 x. The second auxiliary electrodelayers 200 are formed of the same light reflecting material as that ofthe pixel electrodes 119. The width of the first auxiliary electrodelayer 135 in the row direction, exclusive of minute differences whichmay be generated due to influences of a manufacturing step to bedescribed later, is the same as the width of the second auxiliaryelectrode layer 200 in the row direction.

Between the adjacent pixel electrodes 119 is provided a bank which is ofan insulating layer type and extends in a line shape. In addition,between the pixel electrode 119 and the first auxiliary electrode layer135 adjacent to each other, also, there is provided a bank which is ofan insulating layer type and extends in a line shape.

The pixel electrode 119 and the pixel electrode 119 adjacent thereto areinsulated from each other. In addition, the pixel electrode 119 and thesecond auxiliary electrode layer 200 or first auxiliary electrode layer135 adjacent thereto are also insulated from each other.

Over those regions on the substrate 100 x which are located between onepixel electrode 119 and the pixel electrode 119 adjacent to thereto inthe row direction (between a row-directional outer edge 119 a 3 of onepixel electrode 119 and a row-directional outer edge 119 a 4 of thepixel electrode 119 adjacent to the one pixel electrode in the rowdirection) and between one pixel electrode 119 and the first auxiliaryelectrode layer 135 adjacent thereto in the row direction (between arow-directional outer edge 119 a 3 of one pixel electrode 119 and arow-directional outer edge 135 a 2 of the first auxiliary electrodelayer 135 adjacent to the pixel electrode in the row direction, andbetween a row-directional outer edge 119 a 4 of one pixel electrode 119and a row-directional outer edge 135 a 1 of the first auxiliaryelectrode layer 135 adjacent to the pixel electrode 119 in the rowdirection), there are juxtaposedly provided a plurality of column banks522Y which each extend in the column direction (the Y-direction in FIG.3). Therefore, row-directional outer edges of the self-luminescenceregions 100 a are defined by row-directional outer edges of the columnbanks 522Y.

On the other hand, over those regions on the substrate 100 x which areeach located between one pixel electrode 119 and the pixel electrode 119adjacent thereto in the column direction (between a column-directionouter edge 119 a 2 of one pixel electrode 119 and a column-directionouter edge 119 a 1 of the pixel electrode 119 adjacent to the one pixelelectrode 119), there are juxtaposedly provided a plurality of row banks122X which each extend in the row direction (the X-direction in FIG. 3).The region in which the row bank 122X is formed becomes anon-self-luminescence region 100 b, since organic electroluminescence isnot generated in the light emitting layer 123 over the pixel electrode119 in the region. Therefore, column-direction outer edges of theself-luminescence regions 100 a are defined by column-direction outeredges of the row banks 122X.

Where a space between the adjacent column banks 522Y is defined as a gap522 z, the gaps 522 z include red gaps 522zR corresponding to theself-luminescence regions 100aR, green gaps 522zG corresponding to theself-luminescence regions 100aG, blue gaps 522zB corresponding to theself-luminescence regions 100aB, and auxiliary gaps 522zA correspondingto regions in which the first auxiliary electrode layers 135 aredisposed (where the gap 522zR, the gap 522zG, the gap 522zB and the gap522zA are not discriminated from one another, they will hereinafter bereferred to as “gaps 522 z”), and the display panel 10 has aconfiguration in which multiplicities of the column banks 522Y and thegaps 522 z are alternately aligned.

In the display panel 10, the pluralities of the self-luminescenceregions 100 a and non-self-luminescence regions 100 b are alternatelyaligned in the column direction along the gaps 522zR, the gaps 522zG andthe gaps 522zB. The non-self-luminescence region 100 b is provided witha connection recess (contact hole, not illustrated) for connectionbetween the pixel electrode 119 and the source S1 of the TFT, and isprovided with a contact region (contact window, not illustrated) on thepixel electrode 119 for electrical connection to the pixel electrode119.

In one sub-pixel 100 se, the column bank 522Y provided in the columndirection and the row bank 122X provided in the row direction areorthogonal to each other, and the self-luminescence region 100 a islocated between the row bank 122X and the row bank 122X adjacent to thisrow bank 122X, in the column direction.

1.4 Configuration of Each Section of Display Panel 10

The configuration of the organic EL element 100 in the display panel 10will be described referring to FIGS. 4 and 5. FIG. 4 is a schematicsectional view taken along A1-A1 of FIG. 3. FIG. 5 is an enlarged viewof the vicinity of the second auxiliary electrode layer 200 depicted inFIG. 4.

In the display panel 10 according to the present embodiment, thesubstrate (TFT substrate) formed with thin film transistors isconfigured on the lower side in the Z-axis direction, and the organic ELelement section is configured thereon.

1.4.1 Substrate

(1) Substrate 100 x

The substrate 100 x is a support member of the display panel 10, andincludes a base material (not illustrated) and a TFT layer (notillustrated) formed on the base material.

The base material is a support member of the display panel 10, and isflat plate-like in shape.

The TFT layer includes a plurality of TFTs and a plurality of wiringsinclusive of wiring (for connection of the sources S1 of the TFTs andthe corresponding pixel electrodes 119) which are formed on the upperside of the base material. The TFT is for electrically connecting thepixel electrode 119 corresponding to itself and an external power supplyaccording to a drive signal from an external circuit for the displaypanel 10, and has a multilayer structure including electrodes, asemiconductor layer, an insulating layer and the like. The wirings areelectrically connecting the TFTs, the pixel electrodes 119, the externalpower supply, the external circuit and the like.

(2) Planarizing Layer 118

A planarizing layer 118 is provided on the base material and on theupper side of the TFT layer. The planarizing layer 118 located on theupper side of the substrate 100 x is for planarizing the upper side ofthe substrate 100 x where ruggedness is present due to the TFT layer. Inaddition, the planarizing layer 118 fills up spaces between the wiringsand the TFTs, thereby electrically insulating the wirings and the TFTsfrom one another.

The planarizing layer 118 is provided therein with contact holes (notillustrated) for connection between the pixel electrodes 119 and thewirings connected to the sources S1 of the corresponding pixels, thecontact holes being opened in part over the wirings corresponding to thepixel electrodes 119.

In the case where an upper limit film thickness of the planarizing layer118 is not less than 10 μm, variability in film thickness at the time ofmanufacture is enlarged, and it becomes difficult to control a bottomline width. From the viewpoint of a lowering in productivity due to anincrease in tact, the upper limit film thickness of the planarizinglayer 118 is desirably not more than 7 μm. In addition, the filmthickness of the planarizing layer 118 and the bottom line width shouldbe comparable to each other. When the film thickness of the planarizinglayer 118 is reduced, particularly when the lower limit film thicknessof the planarizing layer 118 is not more than 1 μm, it becomes difficultto obtain a desired bottom line width, due to limitations as toresolution. In the case of a general flat panel display exposureapparatus, the lower limit film thickness of the planarizing layer 118is 2 μm. Therefore, the thickness of the planarizing layer 118 ispreferably, for example, 1 to 10 μm, more preferably 2 to 7 μm.

1.4.2 Organic EL Element Section

(1) Auxiliary Pixel Electrode 150 and Pixel Electrode 119

On the planarizing layer 118 located on the upper side of the substrate100 x, there are provided auxiliary pixel electrodes 150 on a sub-pixel100 se basis, as depicted in FIGS. 4 and 5. Further, the pixelelectrodes 119 are stacked on the auxiliary pixel electrodes 150.

The auxiliary pixel electrode 150 and the pixel electrode 119 are forsupplying carriers to a light emitting layer 123; for example, in thecase where they function as anode, they supply holes to the lightemitting layer 123. In addition, since the display panel 10 is of thetop emission type, the pixel electrode 119 has a light reflectingproperty. The shapes of the auxiliary pixel electrode 150 and the pixelelectrode 119 are, for example, substantially rectangular flatplate-like shapes. The auxiliary pixel electrode 150 and the pixelelectrode 119 are spaced by a spacing λX1 from the adjacent firstauxiliary electrode layer 135 in the row direction. In addition, theauxiliary pixel electrode 150 and the pixel electrode 119 are spaced bya spacing λX2 from the adjacent auxiliary pixel electrode 150 and pixelelectrode 119 in the row direction. On the contact hole (notillustrated) of the planarizing layer 118, a connection recess (contacthole, not illustrated) of the pixel electrode 119 that is formed byrecessing part of the pixel electrode 119 in the direction of thesubstrate 100 x side is formed, and the pixel electrode 119 and thewiring connected to the source 51 of the corresponding pixel areconnected at the bottom of the connection recess.

With the auxiliary pixel electrodes 150 formed on the planarizing layer118, adhesion property (close contact property) is enhanced, wherebypenetration of hydrogen into lower layers below the planarizing layer118 can be prevented. When TAOS (Transparent Amorphous OxideSemiconductor) is used for the TFT, deterioration of the TFTs byhydrogen can be restrained.

Note that the auxiliary pixel electrodes 150 may not be formed on theplanarizing layer 118.

(2) First Auxiliary Electrode Layer 135 and Second Auxiliary ElectrodeLayer 200

The first auxiliary electrode layer 135 and the second auxiliaryelectrode layer 200 are auxiliary electrode layers which are disposed toextend in the same layer as that of the auxiliary pixel electrode 150and the pixel electrode 119 over the substrate 100 x, with the commonelectrode layer 125 stacked thereon to contrive electrical connectionwith the common electrode layer 125, for the purpose of reducingelectric resistance in connection with the common electrode layer 125.On the planarizing layer 118 located on the upper side of the substrate100 x, there are provided the first auxiliary electrode layers 135, asdepicted in FIGS. 4 and 5. As depicted in FIG. 4, the first auxiliaryelectrode layer 135 is spaced by a spacing λX1 from the adjacent pixelelectrode 119 in the row direction. Besides, the first auxiliaryelectrode layer 135 is spaced by a spacing from a base portion of theadjacent bank 522 in the row direction, as depicted in FIG. 5.

Here, the thickness of the first auxiliary electrode layer 135 ispreferably 5 to 200 nm; in the present embodiment, the thickness is 50nm, for example.

In addition, as depicted in FIGS. 4 and 5, the second auxiliaryelectrode layers 200 are stacked on the first auxiliary electrode layers135. The width of the second auxiliary electrode layer 200 in the rowdirection is the same as the width of the first auxiliary electrodelayer 135 in the row direction. In other words, the area of the uppersurface of the second auxiliary electrode layer 200 is equivalent to thearea of the upper surface of the first auxiliary electrode layer 135.

The second auxiliary electrode layer 200 contains aluminum as a mainconstituent, and a natural oxide layer of aluminum is formed at least ata surface layer 201 of the second auxiliary electrode layer 200. Thethickness of the natural oxide layer of aluminum is generallyapproximately 3 to 4 nm. The natural oxide layer of aluminum is presentbecause of oxidation of aluminum in the surface layer 201 of the secondauxiliary electrode layer 200 by oxygen in the atmospheric air in theproduction process of the substrate and by oxygen supplied from the sideof the hole injection layer 120B formed over the second auxiliaryelectrode layer 200 in the heating step after formation of the holeinjection layer 120B.

(3) Hole Injection Layer 120

As depicted in FIG. 4, hole injection layers 120 are stacked on thepixel electrodes 119 and on the second auxiliary electrode layers 200.The hole injection layer 120 has a function of transporting holes, whichare injected from the pixel electrode 119, to a hole transport layer121.

The hole injection layers 120 include hole injection layers 120A formedon the pixel electrodes 119 and on the second auxiliary electrode layers200 from a metallic oxide, and hole injection layers 120B stackedindividually on the hole injection layers 120A in the gap 522zR, gap522zG and gap 522zB (which will be described later) from an organicmatter, in this order from the substrate 100 x side. The hole injectionlayers 120A provided in a blue sub-pixel, a green sub-pixel and a redsub-pixel are referred to a hole injection layer 120AB, a hole injectionlayer 120AG and a hole injection layer 120AR, respectively, and the holeinjection layer 120A formed on the second auxiliary electrode layer 200is referred to as a hole injection layer 120AA. In addition, the holeinjection layers 120B provided in the blue sub-pixel, the greensub-pixel and the red sub-pixel are referred to as a hole injectionlayer 120BB, a hole injection layer 120BG and a hole injection layer120BR, respectively.

In the present embodiment, the hole injection layers 120B are providedin a linear shape to extend in the column direction in the gap 522zR,gap 522zG and gap 522zB which will be described later. However, aconfiguration may be adopted in which the hole injection layers 120B areformed only on the hole injection layers 120A formed on the pixelelectrodes 119, and are provided intermittently in the column directionin the gaps 522 z.

(4) Bank 122

As depicted in FIGS. 4 and 5, banks composed of an insulating materialare formed in such a manner as to cover end edges of the pixelelectrodes 119, the hole injection layers 120, the first auxiliaryelectrode layers 135 and the second auxiliary electrode layers 200. Thebanks include column banks 522Y extending in the column direction andprovided in plurality and juxtaposedly in the row direction, and rowbanks 122X extending in the row direction and provided in plurality andjuxtaposedly in the column direction. As depicted in FIG. 3, the columnbanks 522Y are provided in the state of being along the column directionorthogonal to the row banks 122X, and the column banks 522Y and the rowbanks 122X constitute a grid pattern (where the row banks 122X and thecolumn banks 522Y are not discriminated from each other, they willhereinafter referred to as “banks 122”).

The shape of the row bank 122X is a linear shape extending in the rowdirection, and the section of the row bank 122X obtained by cutting inparallel to the column direction is a normal-tapered trapezoid which istapered upward. The row banks 122X are provided in the state of beingalong the row direction orthogonal to the column direction in such amanner as to penetrate each column bank 522Y, and each have an uppersurface below an upper surface 522Yb of the column bank 522Y. Therefore,openings corresponding to the self-luminescence regions 100 a aredefined by the row banks 122X and the column banks 522Y.

The row banks 122X are for controlling flow of inks, which containorganic compounds as materials for the light emitting layers 123, in thecolumn direction. Therefore, the row banks 122X should have an affinityfor the inks of not less than a predetermined value. By such aconfiguration, variations in ink coating amount among sub-pixels isrestrained. The row banks 122X prevent the pixel electrodes 119 frombeing exposed, so that light emission does not occur in regions wherethe row banks 122X are present, and the regions do not contribute toluminance.

The row banks 122X are present over column-directionally outer edges 119a 1 and 119 a 2 of the pixel electrodes 119.

The row banks 122X prevent electric leaks between themselves and thecommon electrode layer 125, and define column-directional outer edges ofthe light emitting region 100 a of each sub-pixel 100 se.

The shape of the column bank 522Y is a linear shape extending in thecolumn direction, and the section of the column bank 522Y obtained bycutting in parallel to the row direction is a normal-tapered trapezoidwhich is tapered upward. The column banks 522Y are for damming up flowof inks, which contain organic compounds as materials for the lightemitting layers 123, in the row direction, thereby definingrow-directional outer edges of the light emitting layers 123 to beformed.

The column banks 522Y have row-directional base portions defined by therow-directional outer edges 119 a 3 and 119 a 4 of the pixel electrodes119 and the row-directional outer edges 135 a 1 and 135 a 2 of the firstauxiliary electrode layers 135. The column banks 522Y prevent electricleaks between themselves and the common electrode layer 125, and definerow-directional outer edges of the light emitting region 100 a of eachsub-pixel 100 se. The column banks 522Y should have a repellency to theinks of not less than a predetermined value.

(5) Hole Transport Layer 121

As depicted in FIG. 4, hole transport layers 121 are stacked on the holeinjection layers 120 in the gaps 522zR, 522zG and 522zB. In addition,the hole transport layers 121 are staked (not illustrated) also on thehole injection layers 120 at the row banks 122X. The hole transportlayer 121 is in contact with the hole injection layer 120B of the holeinjection layer 120. The hole transport layer 121 has a function oftransporting holes, injected from the hole injection layer 120, to thelight emitting layer 123. The hole transport layers 121 provided in thegaps 522zR, 522zG and 522zB are referred to as a hole transport layer121R, a hole transport layer 121G and a hole transport layer 121B,respectively.

In the present embodiment, in the gaps 522 z which will be describedlater, the hole transport layers 121 are provided in a linear shape suchas to extend in the column direction, like the hole injection layers120B. However, the hole transport layers 121 may be providedintermittently in the column direction in the gaps 522 z.

(6) Light Emitting Layer 123

As depicted in FIG. 4, the light emitting layers 123 are stacked on thehole transport layers 121. The light emitting layer 123 is a layercomposed of an organic compound, and has a function of emitting lightthrough recombination of holes and electrons therein. In the gap 522zR,gap 522zG and gap 522zB which are defined by the column banks 522Y, thelight emitting layers 123 are provided in a linear shape such as toextend in the column direction. In a red gap 522zR corresponding to theself-luminescence region 100aR of the red sub-pixel 100seR, a green gap522zG corresponding to the self-luminescence region 100aG of the greensub-pixel 100seG and a blue gap 522zB corresponding to theself-luminescence region 100aB of the blue sub-pixel 100seB, there areformed light emitting layers 123R, 123G and 123B which emit light inrespective colors.

Of the light emitting layer 123, only that part which is supplied withcarriers from the pixel electrode 119 emits light. Therefore, in a rangewhere the row bank 122X as an insulator is present between layers, theelectroluminescence phenomenon of the organic compound does not occur.Accordingly, of the light emitting layer 123, only the part where therow bank 122X is absent emits light, and this part constitutes theself-luminescence region 100a. The column-directional outer edges of theself-luminescence region 100 a are defined by column-directional outeredges of the row banks 122X.

Of the light emitting layer 123, those parts which are located over sidesurfaces and an upper surface of the row bank 122X do not emit light,and these parts constitute non-self-luminescence regions. In theself-luminescence region, the light emitting layer 123 is located on anupper surface of the hole transport layer 121, whereas, in thenon-self-luminescence regions 100 b, the light emitting layer 123 islocated on an upper surface of the hole transport layer 121 on the uppersurface and side surfaces of the row bank 122X (not illustrated).

Note that the light emitting layer 123 extends continuously, not only inthe self-luminescence region 100 a but also to the adjacentnon-self-luminescence regions 100 b. Such a configuration ensures thatat the time of forming the light emitting layer 123, the ink applied tothe self-luminescence region 100 a can flow in the column directionthrough the ink applied to the non-self-luminescence regions 100 b, andthe film thickness can be leveled off among the pixels in the columndirection. It is to be noted, however, that in the non-self-luminescenceregions 100 b, the flow of the ink is moderately restrained by the rowbanks 122X. Therefore, large variability in film thickness is not liableto be generated in the column direction, and variability in luminancefrom pixel to pixel is improved.

(7) Electron Transport Layer 124

As depicted in FIGS. 3, 4 and 5, an electron transport layer 124 isstackedly formed such as to cover the column banks 522Y and the gaps 522z defined by the column banks 522Y. The electron transport layer 124 isformed in the state of being continuous at least over the whole part ofthe display region of the display panel 10. The electron transport layer124 includes an electron transport layer 124A composed of a metallicoxide, fluoride or the like, and an electron transport layer 124Bcontaining an organic matter as a main constituent and stacked on theelectron transport layer 124, in this order from the substrate 100 xside (where the electron transport layers 124A and 124B are genericallyreferred to, they will hereinafter be generically referred to as“electron transport layer 124”).

As depicted in FIGS. 4 and 5, the electron transport layer 124 is formedon the light emitting layers 123. The electron transport layer 124 has afunction of transporting electrons, coming from the common electrodelayer 125, to the light emitting layers 123 and restricting theinjection of electrons into the light emitting layers 123.

As depicted in FIGS. 4 and 5, the electron transport layer 124 is formedalso over the first auxiliary electrode layers 135 and the secondauxiliary electrode layers 200. In the configuration in the presentembodiment in which the hole transport layers 121 are stacked on thesecond auxiliary electrode layers 200, therefore, the electron transportlayer 124 is formed also on upper surfaces of the hole injection layers121. As depicted in FIG. 5, the electron transport layer 124 is lacking(stepping) or thinned at end portions of the first auxiliary electrodelayers 135 and at end portions of the second auxiliary electrode layers200.

Here, “lacking” refers to a state in which part of the electrontransport layer 124 breaks off to be discontinuous and the underlyinglayer is seen there. Due to the lacking, a structure can be realized inwhich the common electrode layer 125 and the first auxiliary electrodelayer 135 make contact with each other at the lacking part of theelectron transport layer 124, and they are electrically connected toeach other there. Therefore, the common electrode layer 125 and thefirst auxiliary electrode layer 135 are connected at a lower electricresistance at the lacking part of the electron transport layer 124 thanat the other parts of the electron transport layer 124.

In addition, “thinning” refers to a state in which part of the electrontransport layer 124, though not reaching a lacking state, is thinned atsectional portions than on upper flat surfaces of the first auxiliaryelectrodes 135 and the second auxiliary electrodes 200, to form thinnedparts. By the thinning, a structure can be realized in which the commonelectrode layer 125 and the first auxiliary electrode layer 135 areelectrically connected with each other at a lower electric resistance atthe thinned part of the electron transport layer 124 than at the otherparts of the electron transport layer 124.

Besides, in the electron transport layer 124, the resistance of theelectron transport layer 124A composed of a metallic oxide, fluoride orthe like is high, and, therefore, a great effect can be obtained by onlylacking or thinning of the electron transport layer 124A.

Therefore, a surface layer 201 of the second auxiliary electrode layer200 and the common electrode layer 125 make contact with each other atside surface portions of the second auxiliary electrode layer 200 whichcorrespond to the lacking or thinned parts of the electron transportlayer 124. However, since an oxide of aluminum is formed at the surfacelayer 201 of the second auxiliary electrode layer 200 as aforementioned,the electric contact resistance between the surface layer 201 of thesecond auxiliary electrode layer 200 and the common electrode layer 125is high.

On the other hand, at partial areas 135 a 1 and 135 a 2 on side surfacesof the first auxiliary electrode layer 135 which correspond to thelacking or thinned parts of the electron transport layer 124, the firstauxiliary electrode layer 135 and at least part of the common electrodelayer 125 are in contact with each other. In these areas, an oxide of ametal is not formed at surface layer portions of the first auxiliaryelectrode layer 135, and, therefore, the electric contact resistancebetween the partial areas 135 a 1 and 135 a 2 on the side surfaces ofthe first auxiliary electrode layer 135 and the common electrode layer125 is low.

In this instance, the electron transport layer 124 which is a functionallayer composed of at least one layer is disposed between the secondauxiliary electrode layer 200 and the common electrode layer 125, andthe thickness of the first auxiliary electrode layer 135 is preferablygreater than the total thickness of the electron transport layer 124. Inother words, the thickness of the first auxiliary electrode layer 135 ispreferably greater than the total thickness of the functional layerwhich is formed by a vacuum deposition method in the state of beingstacked on the first auxiliary electrode layer 135 after the formationof the pixel electrodes 119 (first auxiliary electrode layer 135) andwhich constitutes a high resistance component in electrical contact.

By adopting such a configuration, as depicted in FIG. 5, it is ensuredthat in the partial areas 135 a 1 and 135 a 2 on the side surfaces ofthe first auxiliary electrode layer 135, the first auxiliary electrodelayer 135 and the common electrode layer 125 can be made to contact eachother at a lower resistance than on the upper surface of the firstauxiliary electrode layer 135.

(8) Common Electrode Layer 125

As depicted in FIGS. 4 and 5, the common electrode layer 125 is formedon the electron transport layer 124. The common electrode layer 125constitutes an electrode common to the light emitting layers 123. Thecommon electrode layer 125 includes a common electrode layer 125Acomposed of a metallic oxide, and a common electrode layer 125containing a metal as a main constituent and stacked on the commonelectrode layer 125A in this order from the substrate 100 x side (wherethe common electrode layer 125A and the common electrode layer 125B aregenerically referred to, they will hereinafter be generically referredto as “common electrode layer 125”).

As depicted in FIG. 4, the common electrode layer 125 is formed over thepixel electrodes 119 on the electron transport layer 124. The commonelectrode layer 125 cooperates with the pixel electrode 119 insandwiching the light emitting layer 123 to form a conducting path, forsupplying carriers to the light emitting layer 123; for example, whenfunctioning as a cathode, the common electrode layer 125 supplieselectrons to the light emitting layer 123.

As depicted in FIGS. 4 and 5, the common electrode layer 125A is formedalso in areas over the first auxiliary electrode layers 135 and thesecond auxiliary electrode layers 200. In this instance, the commonelectrode layer 125A makes electrical contact with the partial areas 135a 1 and 135 a 2 on the side surfaces of the first auxiliary electrodelayers 135 which correspond to the lacking or thinned parts of theelectron transport layer 124.

On the other hand, the common electrode layer 125B is mainly formed onlyon the upper surface of the common electrode layer 125A, as depicted inFIGS. 4 and 5.

(9) Sealing Layer 126

A sealing layer 126 is stackedly formed such as to cover the commonelectrode layer 125. The sealing layer 126 is for restraining the lightemitting layers 123 from being deteriorated through contact withmoisture or air. The sealing layer 126 is provided such as to cover theupper surface of the common electrode layer 125.

(10) Bonding Layer 127

On the upper side in the Z-axis direction of the sealing layer 126, acolor filter substrate 131 having color filter layers 128 formed on amain surface on the lower side in the Z-axis direction of an uppersubstrate 130 is disposed, and is bonded to the sealing layer 126 by abonding layer 127. The bonding layer 127 has a function of laminating aback panel, composed of layers ranging from the substrate 100 x to thesealing layer 126, and the color filter substrate 131 with each other,and preventing each of the layers from being exposed to moisture or air.

(11) Upper Substrate 130

The color filter substrate 131 having the color filter layers 128 formedon the upper substrate 130 is disposed on and bonded to the bondinglayer 127. With the upper substrate 130 thus provided, it is possible toenhance rigidity of the display panel 10 and prevent penetration ofmoisture, air or the like.

(12) Color Filter Layer 128

The upper substrate 130 is formed with the color filter layers 128 atpositions corresponding to the color self-luminescence regions 100a. Thecolor filter layers 128 are transparent layers provided for transmittingtherethrough visible lights of wavelengths corresponding to R, G and B,and have a function of permitting the light emitted from each colorpixel to pass therethrough, thereby correcting chromaticity of thelight. For instance, in the present example, red, green and blue filterlayers 128R, 128G and 128B are formed on the upper side of theself-luminescence regions 100aR in the red gaps 522zR, theself-luminescence regions 100aG in the green gaps 522zG and theself-luminescence regions 100aB in the blue gaps 522zB, respectively.

(13) Light-shielding Layer 129

The upper substrate 130 is formed with a light-shielding layer 129 atpositions corresponding to boundaries between the light emitting regions100 a of the pixels. The light-shielding layer 129 is a black resinlayer provided for inhibiting transmission therethrough of visiblelights of wavelengths corresponding to R, G and B, and is formed from,for example, a resin material containing a black pigment excellent inlight-absorbing and light-shielding properties.

1.4.3 Constituent Material of Each Section

An example of constituent materials of the sections depicted in FIGS. 3,4 and 5 will be given below.

(1) Substrate 100 x (TFT Substrate)

The TFT layer has a TFT circuit formed on a base material 100 p, aninorganic insulating layer 116 formed on the TFT circuit, and aplanarizing layer 118. The TFT circuit includes a plurality of TFTs andwiring formed on an upper surface of the base material 100 p. The TFT isfor electrically connecting the pixel electrode 119 corresponding toitself and an external power supply according to a drive signal from anexternal circuit for a light emitting element 100, and has a multilayerstructure including electrodes, a semiconductor layer, an insulatinglayer and the like. The wiring electrically connects the TFTs, the pixelelectrodes 119, the external power supply, the external circuit and thelike.

Known materials can be used for a gate electrode, a gate insulatinglayer, a channel layer, a channel protection layer, a source electrode,a drain electrode and the like which constitute the TFT. As the gateelectrode, a laminated body of copper (Cu) and molybdenum (Mo) isadopted, for example.

For the gate insulating layer 103, there can be used any of knownorganic materials and inorganic materials that have an electricallyinsulating property such as, for example, silicon oxide (SiO₂) andsilicon nitride (SiNx). For the channel layer, there can be adopted atleast one oxide semiconductor selected from among indium (In), gallium(Ga) and zinc (Zn).

For the channel protection layer 106, there can be used, for example,silicon oxynitride (SiON), silicon nitride (SiNx) or aluminum oxide(AlOx). As the source electrode and the drain electrode, there can beadopted, for example, a laminated body of copper-manganese (CuMn) andcopper (Cu) and molybdenum (Mo).

An inorganic insulating layer 116 at an upper portion of the TFT iscomposed of an inorganic compound having a gas barrier property. Forexample, silicon oxide (SiO₂), silicon nitride (SiN), silicon oxynitride(SiON) and silicon oxide (SiO) can be used.

As a connection electrode layer of the TFT, there can be adopted, forexample, a laminated body of molybdenum (Mo), copper (Cu) andcopper-manganese (CuMn). Note that the material to be used forconstituting the connection electrode layer is not limited to this, andcan be appropriately selected from among conductive materials.

As a material for the planarizing layer 118 located on an upper surfaceof the substrate 100 x, there can be used organic compounds such as, forexample, polyimide resins, acrylic resins, siloxane resins, and novolaktype phenolic resins.

(2) Pixel Electrode 119, Auxiliary Pixel Electrode 150, Second AuxiliaryElectrode Layer 200 and First Auxiliary Electrode Layer 135

The pixel electrode 119 is composed of a metallic material. In the caseof the display panel 10 according to the present embodiment, which is ofthe top emission type, by adopting an optical resonator structurethrough optimum thickness setting, the chromaticity of light to beemitted is adjusted and the luminance is enhanced; therefore, a surfaceportion of the pixel electrode 119 should have a reflecting property. Inthe display panel 10 according to the present invention, the pixelelectrode 119 may have a structure in which a plurality of filmsselected from among metal layers, alloy layers and transparentconductive films are stacked. The metal layer can be composed of amaterial having a low sheet resistance and a high light-reflectingproperty, for example, a metallic material containing silver (Ag) oraluminum (Al). For instance, aluminum (Al) alloys have a highreflectance of 80% to 95% and a low electric resistivity of 2.82×10⁻⁸Ωm, and are therefore suitable for use as a material of the secondauxiliary electrode layer 200.

Other than the metal layer of an aluminum alloy or the like, there canbe used, for example, silver, silver-containing alloys and the like,from the viewpoint of high reflectance. As the constituent material ofthe transparent conductive layer, there can be used, for example, ITO(Indium Tin Oxide) and IZO (Indium Zinc Oxide) and the like. Further,metal layers and alloy layers containing aluminum as a main constituentare preferably used, from the viewpoint of cost.

The thickness of the second auxiliary electrode layer 200 is preferably30 to 500 nm, from the viewpoint of reflectance and sheet resistance; inthe present embodiment, the thickness is 100 nm, for example.

The reason is as follows. Since the second auxiliary electrode layer 200is formed simultaneously with, and in the same layer as that of, thepixel electrode 119 on the substrate, the second auxiliary electrodelayer 200 is formed of the same material as that of the pixel electrode119. Therefore, it is the most preferable to use a metal layer or alloylayer containing aluminum as a main constituent as the second auxiliaryelectrode layer 200.

The first auxiliary electrode layer 135 is formed from a material whichcontains as a main constituent a metal different from that of thematerial constituting the second auxiliary electrode layer 200 and whichis lower in contact resistance in air than the material constituting thesecond auxiliary electrode layer 200. Specifically, the first auxiliaryelectrode layer 135 is preferably formed from a metallic material suchas, for example, tungsten (W), chromium (Cr), titanium (Ti), molybdenum(Mo), nickel (Ni), copper (Cu), lanthanum (La), or indium (In). Forinstance, tungsten (W) has a reflectance of 50% to 60% and an electricresistivity of approximately 5.29×10⁻⁸ Ωm, which are inferior to thoseof aluminum (Al), but the first auxiliary electrode layer 135 is stackedwith the upper layer of the second auxiliary electrode layer 200 and canmake electrical contact with the latter. Therefore, the sheet resistanceof the auxiliary electrode can be lowered, and high reflection as thepixel electrode 119 formed in the same layer can also be realized. Forthis reason, tungsten (W) is suitable as a material of the firstauxiliary electrode layer 135 serving as a lower layer. Besides, underthe same thought, a metallic oxide such as ITO and IZO can be used asthe second auxiliary electrode. With such a material used for the firstauxiliary electrode layer 135, it is ensured that although the sheetresistance of the first auxiliary electrode alone is inferior to that ofaluminum, the stacking with the second auxiliary electrode 200 makes itpossible to lower the sheet resistance, and a metallic oxide having ahigh resistance is not liable to be formed at a surface layer part ofthe first auxiliary electrode layer 135. As a result, the good electriccontact resistance between the common electrode layer 125 and thepartial areas 135 a 1 and 135 a 2 on the side surfaces of the firstauxiliary electrode layer 135 which make contact with the commonelectrode layer 125 can be further lowered.

The thickness of the first auxiliary electrode layer 135 is preferably 5to 200 nm, as aforementioned; in the present embodiment, the thicknessis 50 nm, for example.

(3) Hole Injection Layer 120

The hole injection layer 120A is a layer composed of an oxide of, forexample, silver (Ag), molybdenum (Mo), chromium (Cr), vanadium (V),tungsten (W), nickel (Ni), iridium (Ir) or the like. In the case wherethe hole injection layer 120A is composed of an oxide of a transitionmetal, the transition metal can take a plurality of oxidation numbersand, hence, can take a plurality of levels, with the result that holeinjection is facilitated and a driving voltage can be lowered.

In the present embodiment, the hole injection layer 120A included anoxide of tungsten (W) (in the composition formula WOx, x is a realnumber in the range of approximately 2<x<3). In this case, in relationto the oxidation number of tungsten (W), as the ratio (W⁵⁺/W⁶⁺) ofpentavalent tungsten atoms to hexavalent tungsten atoms is higher, thedriving voltage for the organic EL element is lower; therefore, it ispreferable that the tungsten oxide contains pentavalent tungsten atomsin a large amount of not less than a predetermined value. The holeinjection layer 120A is configured as a tungsten oxide layer having afilm thickness of 2 to 30 nm (here, 10 nm, for example). While the holeinjection layer 120A is desirably formed of tungsten oxide, it maycontain extremely minute amounts of impurities in such an extent as tobe mixed ordinarily. When film thickness is not less than 2 nm, uniformfilm formation can be easily realized, and Schottky ohmic connectionbetween an anode 2 and the hole injection layer 120 (described later)can be easily formed; therefore, a film thickness of not less than 2 nmis preferable. Since the Schottky ohmic connection is formed stably whenthe tungsten film thickness is not less than 2 nm, if the hole injectionlayer 120 is formed in a film thickness of not less than 2 nm, stableand efficient injection of holes from the pixel electrode 119 into thehole injection layer 120 can be expected through utilization of theSchottky ohmic connection. Here, “Schottky ohmic connection” refers toconnection in which the difference between the Fermi level of the pixelelectrode 119 and the lowest binding energy of occupied levels in thevicinity of the Fermi surface of the hole injection layer 120aforementioned is not more than a predetermined value.

As the hole injection layer 120B, there can be used, for example, acoating film formed from an organic polymer solution of a conductivepolymer material such as PEDOT (a mixture of polythiophene andpolystyrenesulfonic acid), as aforementioned. In addition, where thehole injection layers 120B provided in the blue sub-pixel, the greensub-pixel and the red sub-pixel are referred to respectively as holeinjection layers 120BB, 120BG and 120BR, as depicted in FIG. 4, thethickness of the hole injection layer 120BR is greater than thethickness of the hole injection layer 120BB and the thickness of thehole injection layer 120BG. It is preferable that the thickness of thehole injection layer 120BB is greater than 0 nm and not more than 25 nm,the thickness of the hole injection layer 120BG is greater than 0 nm andnot more than 30 nm, and the thickness of the hole injection layer 120BRis 20 to 50 nm.

(4) Bank 122

The banks 122 are formed by use of an organic material such as resin,and has an insulating property.

Alternatively, the banks 122 may be formed by use of an inorganicmaterial; in this case, it is preferable to use, for example, siliconoxide (SiO) from the viewpoint of refractive index. Alternatively, suchan inorganic material as silicon nitride (SiN) or silicon oxynitride(SiON) is used to form the banks 122.

Further, since the banks 122 may be subjected to an etching treatment, abaking treatment or the like during manufacturing step, the banks 122are preferably formed by use of a material high in durability such asnot to be excessively deformed or denatured by these treatments.

In addition, surfaces of the banks 122 may be subjected to a fluorinetreatment for imparting water repellency to the surfaces. Besides, thebanks 122 may be formed using a fluorine-containing material. Further,in order to lower water repellency of the surfaces of the banks 122, thebanks 122 may be subjected to irradiation with UV (Ultraviolet) rays ora baking treatment at a low temperature.

(5) Hole Transport Layer 121

The hole transport layers 121 may be formed by use of a high-molecularcompound such as, for example, polyolefins and their derivatives, andpolyarylamines, which are amine-based organic polymers, and theirderivatives. Where the hole transport layers 121 provided in a bluesub-pixel, a green sub-pixel and a red sub-pixel are referred to as ahole transport layer 121B, a hole transport layer 121G and a holetransport layer 121R as depicted in FIG. 4, the film thickness of themis preferably in the range of approximately 10 to 30 nm.

(6) Light Emitting Layer 123

The light emitting layers 123 have a function of emitting light bygeneration of an excited state through recombination of holes andelectrons injected thereinto. The materials to be used for forming thelight emitting layers 123 should be light transmitting organic materialswhich can be formed into a film by a wet type printing method.

(7) Electron Transport Layer 124

For the electron transport layer 124, an organic material having a highelectron transporting property is used. The electron transport layer124A may include a layer formed from sodium fluoride. Examples of theorganic material to be used for the electron transport layer 124Binclude 7E electron low-molecular-weight organic materials. The electrontransport layer 124A is formed in a film thickness in the range of 1 to10 nm.

In addition, the electron transport layer 124B may include a layerformed from a highly electron-transporting organic material doped with adopant metal selected from among alkali metals and alkaline earthmetals. In the embodiment, doping with Ba is adopted. The Ba dopingconcentration is not more than 40 wt %, preferably not more than 20 wt%, and more preferably not more than 15 wt %. The film thickness of theelectron transport layer 124B is in the range of 10 to 50 nm. In thepresent embodiment, the electron transport layer 124B was formed in afilm thickness of approximately 30 nm.

(8) Common Electrode Layer 125

The common electrode layer 125A is formed by use of a light-transmittingconductive material such as, for example, indium tin oxide (ITO) orindium zinc oxide (IZO).

The common electrode layer 125B is formed by use of a thinned electrodeof silver (Ag), aluminum (Al) or the like.

(9) Sealing Layer 126

The sealing layer 126 has a function of restraining organic layers suchas the light emitting layers 123 from being exposed to moisture or air,and is formed by using a light-transmitting material such as, forexample, silicon nitride (SiN) or silicon oxynitride (SiON). Inaddition, a sealing resin layer composed of a resin material such asacrylic resins and silicone resins may be formed on a layer formed byuse of such a material as silicon nitride (SiN) or silicon oxynitride(SiON).

In the case of the display panel 10 according to the present embodimentwhich is of the top emission type, the sealing layer 126 should beformed of a light-transmitting material.

(10) Bonding Layer 127

The material for forming the bonding layer 127 is, for example, a resinadhesive or the like.

(11) Upper Substrate 130

As the upper substrate 130, there can be adopted substrates oflight-transmitting materials such as glass substrates, quartz substrate,and plastic substrates.

(12) Color Filter Layer 128

For the color filter layer 128, there can be adopted known resinmaterials (commercialized resin materials include Color Resist, made byJSR Corporation).

(13) Light-shielding Layer 129

The light-shielding layer 129 is formed from a resin material containinga UV-curing resin (for example, a UV-curing acrylic resin) as a mainconstituent to which a black pigment is added. As the black pigment,there can be adopted light-shielding materials such as carbon blackpigments, titanium black pigments, metallic oxide pigments, and organicpigments.

2. Method of Manufacturing Display Panel 10

A method of manufacturing the display panel 10 will be described belowreferring to FIGS. 6A to 11. FIGS. 6A to 11 each depict a schematicsectional view taken at the same position as line A1-A1 of FIG. 3,depicting a state in each step in manufacture of the display panel 10.

(1) Preparation of Substrate 100 x

A substrate 100 x formed with a plurality of TFTs and wiring isprepared. The substrate 100 x can be manufactured by a known TFTmanufacturing method (FIG. 6A).

(2) Formation of Planarizing Layer 118

A constituent material (photosensitive resin material) of theaforementioned planarizing layer 118 as a photoresist is applied to thesubstrate 100 x in such a manner as to cover the substrate 100 x, toplanarize the surface of the substrate 100 x, thereby forming aplanarizing layer 118 (FIG. 6B).

Formation of contact holes (not illustrated) is conducted by thefollowing process. First, after the planarizing layer 118 is formed, aphotomask provided with predetermined openings is placed thereon, andirradiation with UV rays from above is conducted to expose theplanarizing layer 118, thereby transferring the pattern possessed by thephotomask. Thereafter, development is conducted, to form the planarizinglayer 118 in which the contact holes have been patterned. Wiring on thesubstrate 100 x is exposed at bottom portions of the contact holes.While the planarizing layer 118 is formed by use of a positive typephotoresist, the planarizing layer 118 may be formed by use of anegative type photoresist.

(3) Formation of Auxiliary Pixel Electrodes 150, First AuxiliaryElectrode Layer 135, Pixel Electrodes 119, Second Auxiliary ElectrodeLayer 200 and Hole Injection Layer 120A

After a metal film is stackedly formed by use of a vapor phase growthmethod such as a sputtering method and a vacuum deposition method,patterning is performed by a photolithographic method and an etchingmethod.

Specifically, first, the planarizing layer 118 formed with the contactholes is formed, after which the surface of the planarizing layer 118 issubjected to a dry etching treatment, thereby performingpre-film-formation cleaning.

Next, a first metal layer 150 x for forming auxiliary pixel electrodes150 and a first auxiliary electrode layer 135 is formed on the surfaceof the planarizing layer 118 by a vapor phase growth method such as asputtering method or a vacuum deposition method (FIG. 6C). In thisexample, a film of tungsten is formed by a sputtering method.

Further, the surface of the first metal layer 150 x is subjected topre-film-formation cleaning, after which a second metal layer 119 x forforming pixel electrodes 119 and a second auxiliary electrode layer 200is formed on the surface of the first metal layer 150 x by a vapor phasegrowth method (FIG. 6C). In this example, a film of aluminum or an alloycontaining aluminum as a main constituent is formed by a sputteringmethod.

Furthermore, the surface of the second metal layer 119 x is subjected topre-film-formation cleaning, after which a third metal layer 120Ax forforming a hole injection layer 120A is formed on the surface of thesecond metal layer 119 x by a vapor phase growth method (FIG. 6C). Inthis example, a film of tungsten is formed by a sputtering method.

Thereafter, a photoresist layer FR composed of a photosensitive resin isformed by coating, after which a photomask PM formed with predeterminedopenings is placed thereon, and irradiation with UV rays from above isconducted to expose the photoresist, thereby transferring a patternpossessed by the photomask to the photoresist (FIG. 6D). Next, thephotoresist layer FR is patterned by development.

Thereafter, through the photoresist layer FR thus patterned, the thirdmetal layer 120Ax is patterned by a dry etching treatment, therebyforming the hole injection layers 120A.

Subsequently, through the photoresist layer FR and the hole injectionlayer 120A thus patterned, the second metal layer 119 x is patterned bya wet etching treatment, thereby forming the pixel electrodes 119 andthe second auxiliary electrode layers 200. In this instance, the secondauxiliary electrode layers 200 patterned by the wet etching treatmentmay be over-etched by several micrometers, as compared to the secondmetal layer 119x, the hole injection layers 120A and the first auxiliaryelectrode layers 135 which are patterned by a dry etching treatment. Inthe present disclosure, it is essential that the second auxiliaryelectrode layers 200 are superposed on the first auxiliary electrodelayers 135. It is natural that the superposed state permits the secondauxiliary electrode layers 200 to be over-etched by several micrometersas compared to the first auxiliary electrode layers 135.

Further, subsequently, through the photoresist layer FR, the holeinjection layers 120A, the pixel electrodes 119 and the second auxiliaryelectrode layers 200 thus patterned, the first metal layer 150 x ispatterned by a drying etching method, to form the auxiliary pixelelectrodes 150 and the first auxiliary electrode layers 135. The reasonwhy the dry etching treatment is conducted lies in that tungsten andtungsten oxide film are largely different from the aluminum alloy in wetetching rate and it is therefore difficult to treat them all together.While the dry etching in argon gas or the like is used for tungsten andtungsten oxide and the wet etching is used for the aluminum alloy in thepresent embodiment, this is not restrictive.

In the present embodiment, by forming and baking the hole injectionlayer 120A under predetermined conditions, the hole injection layer 120composed of a tungsten oxide film containing tungsten oxide having anoxygen defect structure is formed, thereby forming the aforementionedoccupied levels.

Here, it is preferable to form the film by a reactive sputtering method,since generation of variability in film formation is restrained thereby.Specifically, a reactive sputtering process is conducted with metallictungsten as a target. Argon gas as a sputtering gas and oxygen gas as areactive gas are introduced into a chamber. In this state, argon isionized by a high voltage, and argon atoms are made to collide againstthe target. Metallic tungsten released by a sputtering phenomenon reactswith oxygen gas to become tungsten oxide, whereby a film is formed. Notethat the film forming conditions in this instance are preferably set toa so-called low-rate condition.

Further, the tungsten oxide film thus formed may be subjected toindividual baking steps. In this instance, formation of the tungstenoxide film may be conducted in a plurality of runs according to the filmthickness, a baking step may be performed after each film forming step,and the film forming step and the baking step may be repeated multipletimes. By this, film density is enhanced, and dissolution resistance isimparted to the film. Specifically, the hole injection layers 120A aresubjected to a baking step (a step of baking in air at a heatingtemperature of 200° C. to 230° C. for a heating time of 15 to 45minutes) under predetermined conditions after the formation of thetungsten oxide film, for realizing vitrification or densification. Bythis, the film density is increased to within the range of 5.8 to 6.0g/cm³. With the film density thus increased, dissolution resistanceagainst an etching liquid or a cleaning liquid used in a bank formingstep in manufacture is imparted to the film, and film consumption isrestrained. Based on the above-mentioned baking conditions, the oxygendefect structure in the film is maintained even upon the baking step, sothat the occupied levels are retained, and hole injection characteristicis prevented from being lowered. In this way, a process for realizingboth good hole injection characteristics and dissolution resistance isused. However, a process may be adopted in which a tungsten film with athickness of approximately 2 nm is formed by a sputtering, followed bybaking in air at a heating temperature of 200° C. to 230° C., to obtaina monolayer film of tungsten oxide, or in which such tungsten filmformation and baking are repeated multiple times to obtain a tungstenoxide film with a desired thickness.

Finally, the photoresist film FR is peeled, to form stacked bodies ofthe auxiliary pixel electrodes 150, the pixel electrodes 119 and thehole injection layer 120A which are patterned in the same shape, as wellas stacked bodies of the first auxiliary electrode layers 135, thesecond auxiliary electrode layers 200 and the hole injection layer 120Awhich are patterned in the same shape (FIG. 7A).

In this instance, a metal film is formed along inner walls of thecontact holes, to form connection recesses for the auxiliary pixelelectrodes 150.

The auxiliary pixel electrodes 150 make contact with the wiring on thesubstrate 100 x exposed at bottom portions of the contact holes, and arein the state of being electrically connected to the electrodes of theTFTs.

(4) Formation of Banks 122

After the hole injection layers 120A of the hole injection layers 120are formed, the banks 122 are formed such as to over the hole injectionlayers 120A. In the formation of the banks 122, row banks 122X are firstformed, after which column banks 522Y are formed such as to form gaps522Z (FIG. 7B).

In forming the banks 122, first, a film composed of a constituentmaterial of the banks 122 (for example, a photosensitive resin material)is stackedly formed on the hole injection layers 120A by use of a spincoating method or the like. Then, the resin film is patterned to formthe row banks 122X and the column banks 522Y sequentially. Thepatterning of the row banks 122X and the column banks 522Y is conductedby performing exposure utilizing a photomask on over the resin film, andperforming a developing step and a baking step (approximately 230° C.,approximately 60 minutes).

Specifically, in the step of forming the row banks 122X, first, aphotosensitive resin film composed of an organic photosensitive resinmaterial such as acrylic resin, polyimide resin or novolak type phenolicresin is formed. Thereafter, drying is conducted to volatilize thesolvent to a certain extent, after which a photomask provided withpredetermined openings is laid on the resin film, and irradiation withUV rays from above is performed to expose the photoresist composed ofthe photosensitive resin or the like to the light, whereby a patternpossessed by the photomask is transferred to the photoresist. Next, thephotosensitive resin is developed, to form an insulating layer in whichthe row banks 122X have been patterned. A so-called positive typephotoresist is used. In the case of the positive type, those partsexposed to light are removed by development. Those parts which are notexposed to light remain without being removed by development.

Here, in forming the hole injection layers 120A, a film composed of ametal (for example, tungsten) is formed by use of a sputtering method ora vapor phase growth method such as a vacuum deposition method, followedby patterning the film on a pixel basis by use of a photolithographicmethod and an etching method, as aforementioned. In this case, in abaking step of the row banks 122X and the column banks 522Y, the metalis oxidized, to form the hole injection layers 120A completely.

In the step of forming the column banks 522Y, first, a film composed ofa constituent material of the column banks 522Y (for example, aphotosensitive resin material) is stackedly formed by use of a spincoating method or the like. Then, the resin film is patterned to opengaps 522 z, thereby forming the column banks 522Y. The formation of thegaps 522 z is conducted by performing exposure to light by disposing amask over the resin film, followed by development. The column banks 522Yextend in the column direction, and are juxtaposedly arrayed in the rowdirection through the gaps 522 z.

(5) Formation of Organic Functional Layer

On the hole injection layers 120A of the hole injection layers 120formed in the gaps 522 z defined by the column banks 522Y inclusive ofthe areas on the row banks 122X, the hole injection layers 120B of thehole injection layers 120 and the hole transport layers 121 and thelight emitting layers 123 are sequentially stackedly formed (FIG. 7C).

In forming the hole injection layers 120B, an ink containing aconductive polymer material such as PEDOT (a mixture of polythiopheneand polystyrenesulfonic acid) is applied to the inside of the gaps 522 zdefined by the column banks 522Y by use of an ink jet method, followedby evaporating off the solvent or by baking. Thereafter, patterning on apixel basis may be performed by use of a photolithographic method and anetching method.

In forming the hole transport layers 121, an ink containing aconstituent material thereof is applied to the inside of the gaps 522 zdefined by the column banks 522Y by use of a wet process such as an inkjet method or a gravure printing method, followed by evaporating off thesolvent or by baking (FIG. 8A). The method for applying the ink of thehole transport layers 121 to the inside of the gaps 522 z is the same asthat in the case of the hole injection layers 120B mentioned above.Alternatively, a film composed of a metal (for example, tungsten) isdeposited by use of a sputtering method, and is oxidized by baking.Thereafter, patterning on a pixel basis may be conducted by use of aphotolithographic method and an etching method.

The light emitting layers 123 are formed by applying inks containing theconstituent materials thereof to the gaps 522 z defined by the columnbanks 522Y by use of an ink jet method, followed by baking (FIG. 8A).Specifically, in this step, an ink 123RI, 123GI or 123BI containing amaterial for an organic light emitting layer for one of R, G and B isplaced to fill the gaps 522 z to be sub-pixel forming regions by an inkjet method, and the ink filling the gaps 522 z is dried under a reducedpressure, followed by a baking treatment, to form one kind of the lightemitting layers 123R, 123G or 123B. In this instance, in application ofthe ink of the light emitting layers 123, first, a solution for formingthe light emitting layers 123 is applied by use of a droplet jettingdevice. When the application of the ink for forming one kind of redlight emitting layers, green light emitting layers and blue lightemitting layers on the substrate 100 x is finished, an ink of anothercolor is next applied to the substrate, and, subsequently, an ink of thethird color is applied to the substrate; in this way, the ink applyingstep is repeated, to sequentially apply three color inks. As a result,the red light emitting layers, the green light emitting layers and theblue light emitting layers are formed on the substrate 100 x in thestate of being repeatedly arrayed in the horizontal direction on thepaper surface of the drawing. The details of the method for applyingeach of the inks of the light emitting layers 123 to the inside of thegaps 522 z are the same as those in the method for forming the holeinjection layers 120B described above.

The method for forming the hole injection layers 120B of the holeinjection layers 120, the hole transport layers 121 and the lightemitting layers 123 is not limited to the above-mentioned method. Otherthan the ink jet method and the gravure printing method, there may alsobe used such known methods as a dispenser method, a nozzle coatingmethod, a spin coating method, intaglio printing, and relief printing,to drop or apply the inks.

As depicted in FIGS. 3, 4 and 5, the electron transport layer 124 isstackedly formed such as to cover the column banks 522Y and the gaps 522z defined by the column banks 522Y. The electron transport layer 124 isformed in the state of being continuous over at least the whole area ofa display region of the display panel 10. The electron transport layer124 includes an electron transport layer 124A composed of a metallicoxide, fluoride or the like, and an electron transport layer 124Bcontaining an organic matter as a main constituent and stacked on theelectron transport layer 124A, in this order from the substrate 100 xside (where the electron transport layers 124A and 124B are genericallyreferred to, they will hereinafter be generically referred to as“electron transport layer 124”).

(6) Formation of Electron Transport Layer 124

After the light emitting layers 123 are formed, the electron transportlayer 124 is formed over the whole area of a light emitting area(display region) of the display panel 10 by a vacuum deposition methodor the like (FIG. 8B). The vacuum deposition method is used, on onehand, for preventing the light emitting layers 123, which are organicfilms, from being damaged. On the other hand, the vacuum depositionmethod is used for the following reason. In the vacuum depositionmethod, the molecules relevant to film formation go straight in thevertical direction toward the substrate, to form a film. Therefore, inpartial areas 135 a 1 and 135 a 2 of stepped surfaces of the firstauxiliary electrodes 135 and the second auxiliary electrodes 200 in thepresent embodiment, film formation is less liable to occur, and the filmcan be made to be lacking (stepping) or thinned there. The electrontransport layer 124 includes the electron transport layer 124A composedof a metallic oxide, fluoride or the like, and the electron transportlayer 124B containing an organic matter as a main constituent andstacked on the electron transport layer 124B, in this order from thesubstrate 100 x side. The electron transport layer 124A is formed on thelight emitting layers 123 by depositing a metallic oxide or fluoride ina film thickness of, for example, 1 to 10 nm by a vacuum depositionmethod or the like. On the electron transport layer 124A, the electrontransport layer 124B is formed in a film thickness of, for example, 10to 50 nm by a co-evaporation method of an organic material and ametallic material. The electron transport layer 124 is formed also onthe second auxiliary electrode layers 200 and the first auxiliaryelectrode layers 135 (exclusive of those areas on the first auxiliaryelectrode layers 135 in which the second auxiliary electrode layers 200are formed). In this instance, the electron transport layer 124 isformed to be lacking (stepping) or thinned at end portions of the firstauxiliary electrode layers 135 and end portions of the second auxiliaryelectrode layers 200. Note that the film thicknesses of the electrontransport layers 124A and 124B are merely illustrative and notrestrictive; thus, suitable film thicknesses which are most advantageousfrom the viewpoint of optical take-out of light are adopted.

(7) Formation of Common Electrode Layer 125

After the electron transport layer 124 is formed, the common electrodelayer 125 is formed such as to cover the electron transport layer 124.The common electrode layer 125 includes a common electrode layer 125Acomposed of a metallic oxide, and a common electrode layer 125B composedof a metal as a main constituent and stacked on the common electrodelayer 125A, in this order from the substrate 100 x side.

First, the common electrode layer 125A is formed such as to cover theelectron transport layer 124 by a sputtering method or the like (FIG.8C). In this example, as the common electrode layer 125A, a transparentconductive layer of ITO, IZO or the like is formed by a sputteringmethod or the like. In this instance, the common electrode layer 125A isformed also in areas over the first auxiliary electrode layers 135 andthe second auxiliary electrode layers 200. In the film forming techniqueby sputtering, a film is liable to be isotropically formed throughcoming-around of atoms. Therefore, the common electrode layer 125A makescontact with those partial areas 135 a 1 and 135 a 2 on side surfaces ofthe first auxiliary electrode layers 135 which corresponding to thelacking or thinned parts of the electron transport layer 124, asdepicted in FIGS. 4 and 5. It is important that the electron transportlayer 124 is formed to be partially lacking or thinned by use of vacuumdeposition, whereas the common electrode layer is formed throughcoming-around film formation by sputtering which is high in coverageproperty.

Here, the method of forming the common electrode layer 125 will bedescribed further.

First, referring to FIG. 11, general configuration of a sputteringsystem 600 will be described. The sputtering system 600 includes asubstrate transfer chamber 610, a film forming chamber 620, and a loadlock chamber 630, and sputtering is conducted in the film formingchamber 620 by a magnetron sputtering method. A sputtering gas isintroduced into the film forming chamber 620. An inert gas such as Ar(argon) gas is used as the sputtering gas. In the present embodiment, Ar(argon) is used.

A substrate 622 on which to form a film is placed on a carrier 621 inthe sputtering system 600. In the substrate transfer chamber 610, thesubstrate 622 is mounted to the carrier 621 by a substrate pushing-upmechanism 611. The carrier 621 with the substrate 622 mounted thereto ismoved rectilinearly on a carrying passage 601 at a constant speed, fromthe substrate transfer chamber 610 through the film forming chamber 620into the load lock chamber 630. In the present embodiment, the movingspeed of the carrier 621 is 30 mm/second. Note that the substrate 622 isnot heated, and the sputtering is conducted at normal temperature.

In the film forming chamber 620, a rod-shaped target 623 extending in adirection orthogonal to the carrying passage 601 is disposed. In thepresent embodiment, the target 623 is ITO or IZO. Note that the target623 may not necessarily be rod-shaped, and may be, for example, in apowdery form.

A power supply 624 impresses a voltage on the target 623. Note thatwhile the power supply 624 in FIG. 11 is an AC (Alternating Current)power supply, it may be a DC (Direct Current) power supply or a DC/AChybrid power supply.

The inside of the sputtering system 600 is evacuated by an evacuationsystem 631, and the sputtering gas is introduced into the film formingchamber 620 by a gas supply system 632. When a voltage is impressed onthe target 623 by the power supply 624, a plasma of the sputtering gasis generated, and the surface of the target 623 is sputtered. Then, thesputtered atoms of the target 623 are deposited on the substrate 622,whereby a film is formed.

Note that the gas pressure of Ar (argon) as the sputtering gas is, forexample, 0.6 Pa, and its flow rate is 100 sccm.

Next, the common electrode layer 125B is formed on the common electrodelayer 125A by a CVD (Chemical Vapor Deposition) method, a sputteringmethod or a vacuum deposition method (FIG. 8C). In this example, thecommon electrode layer 125B is formed by depositing silver by a vacuumdeposition method. As depicted in FIGS. 4 and 5, the common electrodelayer 125B is mainly formed only on the upper surface of the commonelectrode layer 125A. Here, if the common electrode layer 125A is formedto be able to make sufficient contact with those partial areas 135al and135 a 2 on the side surfaces of the first auxiliary electrode layers 135which correspond to the lacking or thinned parts of the electrontransport layer 124 by sputtering film formation or the like with highcoverage property, the film formation for forming the common electrodelayer 125B can be conducted by application of a vacuum depositionmethod.

(8) Formation of Sealing Layer 126

After the common electrode layer 125 is formed, the sealing layer 126 isformed such as to cover the common electrode layer 125 (FIG. 8D). Thesealing layer 126 can be formed by a CVD method, a sputtering method orthe like.

(9) Formation of Color Filter Substrate 131

Next, a step of producing the color filter substrate 131 will beexemplified.

The transparent upper substrate 130 is prepared, and a material for thelight-shielding layer 129, which contains a UV-curing resin (e.g.,UV-curing acrylic resin) material as a main constituent with a blackpigment added thereto, is applied to a surface on one side of thetransparent upper substrate 130 (FIG. 9A).

A pattern mask PM provided with predetermined openings is placed on theupper surface of the applied light-shielding layer 129, and irradiationwith UV rays is conducted from above (FIG. 9B).

Thereafter, development is conducted by removing the pattern mask PM anduncured portions of the light-shielding layer 129, and curing isperformed, whereon the light-shielding layer 129 in a substantiallyrectangular sectional shape, for example, is completed (FIG. 9C).

Next, a material 128G for a color filter layer 128 (e.g., 128G), whichcontains a UV-curing resin component as a main constituent, is appliedto the surface of the upper substrate 130 formed with thelight-shielding layer 129 (FIG. 9D), a predetermined pattern mask PM isplaced thereon, and irradiation with UV rays is conducted (FIG. 9E).

Thereafter, curing is performed, and development is conducted byremoving the pattern mask PM and uncured portions of the paste 128R,whereon color filter layers 128G are formed (FIG. 9F).

The steps of FIGS. 9D, 9E and 9F are similarly repeated for each ofcolor filter materials, whereby color filter layers 128R and 128B areformed (FIG. 9G). Note that commercially available color filter productsmay be utilized, instead of using the paste 128R.

In this way, the color filter substrate 131 is formed.

(10) Lamination of Color Filter Substrate 131 and Back Panel

Next, a material for the bonding layer 127, which contains a UV-curingresin such as acrylic resin, silicone resin and epoxy resin as a mainconstituent, is applied to the back panel including the layers rangingfrom the substrate 100 x to the sealing layer 126 (FIG. 10A).

Subsequently, the applied material is irradiated with UV rays, tolaminate the back panel and the color filter substrate 131 in the statein which they are relatively positioned (aligned). In this instance,care should be taken to prevent gas from entering between bothsubstrates. Thereafter, both the substrates are baked to complete thesealing step, whereon the display panel 10 is completed (FIG. 10B).

3. In Regard of Effect of Display Panel 10

Now, effects obtained from the display panel 10 will be described below.

As a material for the auxiliary electrode layers, a metal layer isformed from a material having a low sheet resistance and a high lightreflecting property, specifically, from a metallic material containingsilver or aluminum. In the case where the auxiliary electrode layers areformed from a metallic material containing aluminum which isinexpensive, there has been a problem that an oxide film is formed at asurface (surface layer) of the auxiliary electrode layers, resulting inthat the contact resistance between the auxiliary electrode layer andthe common electrode layer is high.

In coping with such a problem, the display panel 10 according to thepresent embodiment is an organic EL display panel having a plurality ofpixel electrodes 119 arranged in a matrix pattern on a substrate 100 x,with a light emitting layer 123 disposed on each pixel electrode 119,the light emitting layer 123 containing an organic light emittingmaterial, the organic EL display panel including: the substrate 100 x;the plurality of pixel electrodes 119 arranged in a matrix pattern overthe substrate 100 x; a first auxiliary electrode layer 135 disposed toextend in a column or row direction in at least one of gaps betweenadjacent ones of the pixel electrodes 119 over the substrate 100 x; asecond auxiliary electrode layer 200 that contains aluminum as a mainconstituent and is disposed to be superposed on the first auxiliaryelectrode layer 135; a plurality of light emitting layers 123 disposedon the plurality of pixel electrodes 119; and a common electrode layer125 disposed continuously to cover the first auxiliary electrode layer135 and the second auxiliary electrode layer 200 superposed thereon aswell as the upper side of the plurality of light emitting layers 123. Inaddition, the first auxiliary electrode layer 135 and the commonelectrode layer 125 are in contact with each other at least in partialareas 135 a 1 and 135 a 2 on wall surfaces perpendicular to an uppersurface of the first auxiliary electrode layer 135, and the firstauxiliary electrode layer 135 is composed of a material that contains ametal different from aluminum as a main constituent and is lower thanaluminum in contact resistance in air. Besides, an oxide of aluminum maybe formed at least at a surface layer of the second auxiliary electrodelayer 200.

Here, the second auxiliary electrode layer 200, on a material basis,contains aluminum as a main constituent, and a natural oxide of aluminumis formed at least at a surface layer 201 of the second auxiliaryelectrode layer 200. Moreover, in a heating step after film formationfor forming a hole injection layer 120B over the second auxiliaryelectrode layer 200, at least, aluminum in the surface layer 201 of thesecond auxiliary electrode layer 200 is oxidized by oxygen which issupplied from the hole injection layer 120B side. This is the reason forthe presence of aluminum oxide at the surface layer 201.

On the other hand, the first auxiliary electrode layer 135, on amaterial basis, contains as a main constituent a metal different fromthe material constituting the second auxiliary electrode layer 200, forexample, at least one metal selected from among tungsten, chromium,titanium, molybdenum, nickel, copper, lanthanum and indium.Alternatively, the first auxiliary electrode layer 135 is composed ofITO or IZO. Thus, the first auxiliary electrode layer 135 is composed ofa material which is lower in contact resistance in air than the materialconstituting the second auxiliary electrode layer 200. Since thejust-mentioned metals and oxides are chemically stable at roomtemperature, an oxide of a metal tending to indicate a high resistanceis not liable to be formed at a surface layer part of the firstauxiliary electrode layer 135. Therefore, this part is lower thanaluminum in contact resistance in air. In other words, a configurationis realized in which the resistance in the vicinity of the surface layer201 of the second auxiliary electrode layer 200 is higher than theresistance in the vicinity of the surface layer of the first auxiliaryelectrode layer 135.

By the effect of the structure in the present embodiment, contactresistance has been successfully lowered by at least one order ofmagnitude. Specifically, in the existing case where electrical contactthrough the stepping (lacking) at sections was not provided, the contactresistance was approximately 1,000 to 2,000 MΩ μm², and, in contrast,the contact resistance is approximately 50 to 100 MΩ μm² in the presentembodiment.

On the other hand, on a structural basis, the common electrode layer 125is disposed continuously to cover the first auxiliary electrode layer135 and the second auxiliary electrode layer 200 superposed thereon; inaddition, the first auxiliary electrode layer 135 and the commonelectrode layer 125 are in contact with each other at least in thepartial areas 135 a 1 and 135 a 2 on the wall surfaces perpendicular tothe upper surface of the first auxiliary electrode layer 135.

As a result, it is possible to further lower the electric contactresistance between the common electrode layer 125 and those partialareas 135 a 1 and 135 a 2 of the side surfaces of the first auxiliaryelectrode layer 135 which make contact with the common electrode layer125. In other words, the contact resistance between the first auxiliaryelectrode layer 135 and the common electrode layer 125 can be made lowerthan the contact resistance between the second auxiliary electrode layer200 and the common electrode layer 125.

In addition, in the existing configuration, in the case where thealuminum alloy of the auxiliary electrode layer is oxidized and wherethe auxiliary electrode layer makes electrical contact with the commonelectrode layer locally without intermediate presence of the oxide filmdue to the presence of a defect or foreign matter in the auxiliaryelectrode layer, there arises a fear of concentration of current in thatpart, possibly causing local heat generation or material deterioration,as aforementioned. In the display panel 10, however, it is possible tofurther lower the electric contact resistance between the commonelectrode layer 125 and those partial areas 135 a 1 and 135 a 2 of theside surfaces of the first auxiliary electrode layer 135 which makecontact with the common electrode layer 125. Therefore, even if theauxiliary electrode layer and the common electrode layer make contactwith each other locally without intermediate presence of an oxide film,local concentration of current at that part can be prevented, and localheat generation or material deterioration or the like, which might occurattendant on the current concentration, can be prevented from occurring.

As has been described above, in the display panel 10 according to onemode of the present disclosure, having a configuration in which the samelight-reflecting metallic material as that of pixel electrodes is usedfor the auxiliary electrode layer, the electric contact resistance inelectrical connection between the common electrode layer and theauxiliary electrode layer can be reduced. As a result, light emissionefficiency can be enhanced, and variability in luminance can berestrained.

In addition, in the above-mentioned mode, a configuration may further beadopted in which a functional layer 124 composed of at least one layerdisposed continuously to cover the first auxiliary electrode layer 135and the second auxiliary electrode layer 200 as well as an upper side ofthe plurality of light emitting layers 123 is provided between thesecond auxiliary electrode layer 200 and the common electrode layer 125,the functional layer 124 is lacking or thinned in the vicinity ofpartial areas 135al and 135 a 2 of the first auxiliary electrode layer135, and the thickness of the first auxiliary electrode layer 135 isgreater than the thickness of the functional layer 124.

Further, the same as above applies also to the case where the filmthickness of the electron transport layer is increased to, for example,approximately 100 nm for the purpose of enhancing the optical take-outof light. Where the thickness of the first auxiliary electrode layer 135is set to be greater than the total thickness of the functional layer124 disposed continuously to cover the first auxiliary electrode layer135 and the second auxiliary electrode layer 200 between the secondauxiliary electrode layer 200 and the common electrode layer 125, it isnaturally possible to thereby ensure reliable contact of the commonelectrode layer 125 with the first auxiliary electrode layer 135 in thepartial areas 135 a 1 and 135 a 2 on the wall surfaces perpendicular tothe upper surface of the first auxiliary electrode layer 135, and torealize both a high carrier mobility and a reduction in the electriccontact resistance between the common electrode layer and the auxiliaryelectrode layer.

Furthermore, where the auxiliary pixel electrodes 150 and the firstauxiliary electrodes 135 have the same film thickness and where thepixel electrodes 119 and the second auxiliary electrodes have the samefilm thickness, it is thereby possible to reduce process cost throughforming the same-thickness electrodes as the same layer and in the samestep.

In addition, in the above-mentioned mode, on the basis of optical designof the light emitting section, ITO or IZO or the like may be inserted asan optical adjustment layer between the pixel electrode 119 and the holeinjection layer 120A. In this instance, a transparent conductive layercomposed of ITO or IZO disposed discontinuously over the first auxiliaryelectrode layer 135 and the second auxiliary electrode layer 200 may beprovided between the second auxiliary electrode layer 200 and thefunctional layer 124, at an auxiliary electrode section formed as thesame layer. According to such a configuration, also, the effects of thepresent disclosure are exhibited.

Besides, the method of manufacturing the display panel 10 according tothe present embodiment is a method of manufacturing an organic ELdisplay panel having a plurality of pixel electrodes 119 arranged in amatrix pattern on a substrate 100 x, with a light emitting layer 123disposed on each of the pixel electrodes 119, the light emitting layer123 containing an organic light emitting material, the method includingthe steps of: preparing the substrate 100 x; forming the plurality ofpixel electrodes 119 in a matrix pattern over the substrate 100 x;forming a first auxiliary electrode layer 135 to extend in a column orrow direction in at least one of gaps between adjacent ones of the pixelelectrodes 119 over the substrate 100 x, the first auxiliary electrodelayer 135 composed of a material which contains as a main constituent ametal different from aluminum and is lower than aluminum in contactresistance in air; forming a second auxiliary electrode layer 200containing aluminum as a main constituent on the first auxiliaryelectrode layer 135 in such a manner as to extend in the same directionas the first auxiliary electrode layer 135 and be superposed on thefirst auxiliary electrode layer 135; forming the plurality of lightemitting layers 123 on the plurality of pixel electrodes 119; andforming, by a sputtering method, a common electrode layer 125continuously to cover the first auxiliary electrode layer 135 and thesecond auxiliary electrode layer 200 as well as an upper side of theplurality of light emitting layers 123 in such a manner that the firstauxiliary electrode layer 135 and the common electrode layer 125 makecontact with each other at least in partial areas 135 a 1 and 135 a 2 onwall surfaces perpendicular to an upper surface of the first auxiliaryelectrode layer 135.

In addition, in the above-mentioned mode, the method of manufacturingthe organic EL display panel may include a step of forming a functionallayer 124 continuously to cover the first auxiliary electrode layer 135and the second auxiliary electrode layer 200 as well as an upper side ofthe plurality of light emitting layers 123, between the second auxiliaryelectrode layer 200 and the common electrode layer 125, by a vacuumdeposition method, the functional layer 124 being composed of at leastone layer and being thinner than the first auxiliary electrode layer135. In this instance, the functional layer 124 may be lacking orthinned in the vicinity of partial areas 135al and 135 a 2 of the firstauxiliary electrode layer 135.

According to such a configuration, the thickness of the first auxiliaryelectrode layer 135 is made to be greater than the total thickness ofthe functional layer 124 disposed, by a vapor deposition method,continuously between the second auxiliary electrode layer 200 and thecommon electrode layer 125 (which is formed by the sputtering method),whereby the common electrode layer 125 (formed by the sputtering method)can be reliably put in contact with the functional layer (formed by thevapor deposition method) in those partial areas 135 a 1 and 135 a 2 onwall surfaces perpendicular to the upper surface of the first auxiliaryelectrode layer 135 in which the functional layer 124 is lacking orthinned

As a result, it is possible to manufacture a display panel 10 in whichelectric resistance in electrical connection between a common electrodelayer and an auxiliary electrode layer can be reduced, light emissionefficiency can be enhanced, and variability in luminance can besuppressed.

4. Modifications

While the display panel 10 according to the present embodiment has beendescribed above, the present disclosure is not to be limited to theabove embodiment in any way, except for essential and characteristicconstituent elements thereof. For instance, modes obtained by subjectingthe embodiment to various modifications conceived by those skilled inthe art, and modes realized by arbitrary combinations of configurationalelements and functions of the embodiment without departing from the gistof the present invention are also included in the present disclosure. Asexamples of such modes, modifications of the display panel 10 will nowbe described below.

(1) Modification 1

In the display panel 10, a single stretch of first auxiliary electrodelayer 135 disposed to extend in a column or row direction in at leastone of gaps between adjacent ones of pixel electrodes 119 and a singlestretch of second auxiliary electrode layer 200 disposed to besuperposed on the first auxiliary electrode layer 135 are provided, andthe first auxiliary electrode layer 135 and the common electrode layer125 are in contact with each other at least in the partial areas 135 a 1and 135 a 2 on the side walls perpendicular to the upper surface of thefirst auxiliary electrode layer 135.

However, the plan-view shape of the first auxiliary electrode layer 135and the second auxiliary electrode layer 200 is not limited to theabove-mentioned, and may be changed variously.

FIG. 12A is a schematic plan view depicting the shapes of banks andauxiliary electrode layers in a display panel 10V according toModification 1. FIG. 13A is a schematic sectional view taken along lineA3-A3 of FIG. 12A. As depicted in FIG. 12A, the display panel 10Vaccording to Modification 1 includes two stretches of first auxiliaryelectrode layers 135V1 and 135V2 disposed to extend in a columndirection in a gap between adjacent banks 522Y, and two stretches ofsecond auxiliary electrode layers 200V1 and 200V2 disposed to besuperposed on the first auxiliary electrode layer 135. As depicted inFIG. 13A, two outer edges located on row-directionally outer sides ofthe two stretches of first auxiliary electrode layers 135V1 and 135V2and two stretches of second auxiliary electrode layers 200V1 and 200V2are individually covered by the banks 522Y. In other words, the firstauxiliary electrode layer 135 is in contact with a base portion of thebank 522 adjacent thereto. In addition, natural oxide layers are formedat surface layers 201V1 and 201V2 of the second auxiliary electrodelayers 200V1 and 200V2.

According to such a configuration, in the display panel 10V, as comparedto the display panel 10, it is possible to increase the sectional areaof the auxiliary electrode by an amount corresponding to therow-directional sections of the first auxiliary electrode layer 135V1and the second auxiliary electrode layer 200V1, and to thereby reducethe sheet resistance of the auxiliary electrode. In addition, in thedisplay panel 10V, it is possible to adopt a configuration in which thefirst auxiliary electrode layer 135 and the common electrode layer 125are in contact with each other in partial areas 135Va1 and 135Va2 onrow-directionally opposed side surfaces of the two stretches of firstauxiliary electrode layers 135V1 and 135V2, and it is possible torealize a contact resistance similar to that in the display panel 10.

Note that instead of providing the two stretches of first auxiliaryelectrode layers 135V1 and 135V2 and the two stretches of secondauxiliary electrode layers 200V1 and 200V2, a slit-shaped opening may beprovided in each one of a single stretch of first auxiliary electrodelayer 135 and a single stretch of second auxiliary electrode layer 200.

(2) Modification 2

In a display panel 10W according to Modification 2, a second auxiliaryelectrode layer 200W is provided with through-holes 200X, which aresubstantially circularly shaped holes and are aligned at a predeterminedinterval and in a row in the column direction. FIG. 12B is a schematicplan view depicting the shapes of banks and the auxiliary electrodelayer in the display panel 10W according to Modification 2. FIG. 13B isa schematic sectional view taken along line A4-A4 of FIG. 12B. Asdepicted in FIG. 12B, the display panel 10W according to Modification 2includes a single stretch of first auxiliary electrode layer 135Wdisposed to extend in the column direction in a gap between adjacentbanks 522W, and two stretches of second auxiliary electrode layers 200Wdisposed to be superposed on the first auxiliary electrode layer 135,and a plurality of holes 200Wa and 135Wa penetrating the secondauxiliary electrode layers 200W and the first auxiliary electrode layer135 are provided, in the state of being aligned in the column direction.As depicted in FIG. 13B, natural oxide layers are formed at surfacelayers 201W1 and 201W2 of the second auxiliary electrode layers 200W1and 200W2.

According to such a configuration, in the display panel 10W, the firstauxiliary electrode layer 135 and the common electrode layer 125 are incontact with each other, not only in partial areas 135 a 1 and 135 a 2on side surfaces perpendicular to the upper surfaces of the firstauxiliary electrode layer 135W but also in partial areas 135Wa1 and135Wa2 on inner peripheral surfaces of the holes 135Wa bored in thefirst auxiliary electrode layer 135. For this reason, the contact areacan be increased as compared to the display panel 10, and the contactresistance can be reduced as compared to the display panel 10.

(3) Modification 3

In a display panel 10X according to Modification 3, a second auxiliaryelectrode layer 200X is provided with through-holes 200X, which aresubstantially circularly shaped holes and are aligned at a predeterminedinterval and in two rows in the column direction. FIG. 12C is aschematic plan view depicting the shapes of banks and auxiliaryelectrode layers in the display panel 10 according to Modification 3.Specifically, as the display panel 10X according to Modification 3depicted in FIG. 12C, a configuration may be adopted in which a singlestretch of first auxiliary electrode layer 135X extending in the columndirection in a gap between adjacent banks 522Y, and a single stretch ofsecond auxiliary electrode layer 200X disposed to be superposed on thefirst auxiliary electrode layer 135X, are provided, and a plurality ofholes 200Xa, 135Xa and 200Xb, 135Xb penetrating the second auxiliaryelectrode layer 200X and the first auxiliary electrode layer 135 arealigned in two rows in the column direction.

According to such a configuration, the contact area can be furtherincreased, and the contact resistance can be further reduced, ascompared to the display panel 10W.

(4) Modification 4

In the display panel 10, the first auxiliary electrode layer 135 and thesecond auxiliary electrode layer 200 are disposed to extend in the samelayers as the auxiliary pixel electrodes 150 and the pixel electrodes119, respectively, on the upper surface of the planarizing layer 118over the substrate 100 x, and the common electrode layer 125 issuperposed thereon, to ensure electrical contact with the commonelectrode layer 125.

However, the layers in which the first auxiliary electrode layer 135 andthe second auxiliary electrode layer 200 are to be provided on and overthe substrate 100 x are not limited to the above-mentioned, and may bechanged or added appropriately.

FIG. 14A is a sectional view of the vicinity of a second auxiliaryelectrode layer 200 in a display panel 10Y according to Modification 4.The display panel 10Y is characterized in that in addition to theconfiguration of the display panel 10W, further, a planarizing layer118Y is composed of two layers consisting of a planarizing lower layer118AY and a planarizing upper layer 118BY, and a third current feedingauxiliary electrode layer 135Y is provided between the planarizing lowerlayer 118AY and the planarizing upper layer 118BY.

Specifically, the display panel 10Y includes the planarizing lower layer118AY and the planarizing upper layer 118BY which contain a resin as amain constituent, over a substrate 100 x, and the third current feedingauxiliary electrode layer 135Y which extends in the column direction andis composed of the same material as the first auxiliary electrode layer135W is provided between the planarizing lower layer 118AY and theplanarizing upper layer 118BY. In this instance, the third currentfeeding auxiliary electrode layer 135Y may be enlarged in width in therow direction to a position where it does not overlap with the pixelelectrode 119. In addition, a second auxiliary electrode layer 200W, ahole injection layer 120B, electron transport layers 124A and 124B,common electrode layers 125A and 125B, and a sealing layer 126 aresequentially stacked over the first auxiliary electrode layer 135W.Further, the planarizing upper layer 118BY is provided with a contacthole 118BYa penetrating to the upper surface of the third currentfeeding auxiliary electrode layer 135Y, and the first auxiliaryelectrode layer 135W is disposed to be continuous with an innerperipheral surface of the contact hole 118BYa and a bottom surface ofthe contact hole 118BYa. In addition, the first auxiliary electrodelayer 135W is in contact with the third current feeding auxiliaryelectrode layer 135Y at least in a partial area 135Ya, in the contacthole 118BYa, of the upper surface of the third current feeding auxiliaryelectrode layer 135Y. In this instance, like in Modification 3 describedabove, a functional layer 124 is disposed between the first auxiliaryelectrode layer 135W and the common electrode layer 125, and thethickness of the first auxiliary electrode layer 135W is set greaterthan the thickness of the functional layer 124. Therefore, the firstauxiliary electrode layer 135W is in contact with the common electrodelayer 125B in partial areas 135 a 1 and 135 a 2 on side surfaces.Further, as aforementioned, the first auxiliary electrode layer 135W isin contact with the partial area 135Ya of the third current feedingauxiliary electrode layer 135Y in the contact hole 118BYa. By this, aconfiguration can be obtained in which, even in the case where a naturaloxide layer of aluminum is formed at a surface layer 201W of the secondcurrent feeding auxiliary electrode layer 200W on the first auxiliaryelectrode layer 135W, the common electrode layer 125 and the thirdcurrent feeding auxiliary electrode layer 135Y are electricallyconnected to each other through the first auxiliary electrode layer135Y, along routes C1 and C2 depicted in FIG. 14A, and the third currentfeeding auxiliary electrode layer 135Y can be made to function as acurrent feeding auxiliary electrode for the common electrode layer 125.

As a result, in the display panel 10Y, the sectional area of theauxiliary electrode can be increased by an amount corresponding to therow-directional section of the third current feeding auxiliary electrodelayer 135Y, and the sheet resistance can be reduced, as compared to thedisplay panel 10W. This is effective as means for restraining a loweringin light take-out efficiency which might be generated attendant on anincrease in pixel density (an increase in resolution). In addition, theconfiguration in which the auxiliary electrodes are provided in a layerbetween the planarizing lower layer 118AY on the substrate 100 x and theplanarizing upper layer 118BY ensures that there are is littlepositional limitation due to TFT wiring, and that the degree of freedomin plan-view layout of the third current feeding auxiliary electrodelayer 135Y is enhanced.

Note that the position at which to provide the contact hole 118BYa isnot limited to the above-mentioned one; for example, the contact hole118BYa may be provided at a position different from that in FIG. 14A.

Further, in Modification 4A, by further modifying Modification 4, aconfiguration may be adopted in which the second auxiliary electrodelayer 200W and the hole injection layer 120B are formed by masking theupper surface of the first auxiliary electrode layer 135W in a filmforming step, whereby it is ensured that the second auxiliary electrodelayer 200W and the hole injection layer 120B are not provided on thefirst auxiliary electrode layer 135W. FIG. 14B is a sectional view of adisplay panel 10Y in Modification 4A in which the second auxiliaryelectrode layer 200W and the hole injection layer 120B are not providedon the first auxiliary electrode layer 135W. In such a configuration,electron transport layers 124A and 124B, common electrode layers 125Aand 125B, and a sealing layer 126 are sequentially stacked over thefirst auxiliary electrode layer 135W. In the case where the electrontransport layers 124A and 124B are formed by vapor deposition, they arenot formed on the inner peripheral surface of the contact hole 118BYa.Therefore, by setting the depth of the contact hole 118BYa to be greaterthan the thickness of the common electrode layers 125A and 125B, aconfiguration can be adopted in which partial areas 135 a 3 and 135 a 4of the first auxiliary electrode layer 135 make direct contact with thecommon electrode layer 125B on the inner peripheral surface of thecontact hole 118BYa. Alternatively, in the case where the electrontransport layers 124A and 124B are formed by a sputtering method or aCVD method, a configuration can be adopted in which the first auxiliaryelectrode layer 135W is electrically connected to the common electrodelayer 125B through the electron transport layers 124A and 124B.

According to such a configuration, the contact area between the commonelectrode layer 125 and the first current feeding auxiliary electrodelayer 135W can be increased, and the sectional area of a conducting pathto the third current feeding auxiliary electrode layer 135Y can beincreased. As a result, connection resistance from the common electrodelayer 125 to the current feeding auxiliary electrode can be reduced.

(5) Modification 5

In addition to the configuration of the display panel 10W, further, afourth current feeding auxiliary electrode layer 135Z may be providedbetween a layer and a layer which constitute the substrate 100 x. FIG.15A is a sectional view of the vicinity of a second auxiliary electrodelayer 200 in a display panel 10Z according to Modification 5.

As depicted in FIG. 15A, in the display panel 10Z, the substrate 100 xincludes a base material 100 p, a gate insulating layer 103 and achannel protection layer 106 which constitute a TFT circuit, and aninorganic insulating layer 116 provided over them and containing aninorganic material as a main constituent. A planarizing layer 118Ycontaining a resin as a main constituent is formed over the substrate100 x. The planarizing layer 118 may have a two-layer structure composedof a planarizing lower layer 118AY and a planarizing upper layer 118BY,or may have a monolayer structure.

In the display panel 10Z, the fourth current feeding auxiliary electrodelayer 135Z disposed to extend in a column or row direction is providedbetween layers of a plurality of layers constituting the substrate 100x, for example, between the channel protection layer 106 and theinorganic insulating layer 116. Note that the position at which toprovide the fourth current feeding auxiliary electrode layer 135Zbetween the layers of the plurality of layers in the substrate 100 x isnot limited to the position between the channel protection layer 106 andthe inorganic insulating layer 116. In addition, the fourth currentfeeding auxiliary electrode layer 135Z may be enlarged in width in therow direction to a position where it does not overlap with a pixelelectrode 119.

A second auxiliary electrode layer 200W, a hole injection layer 120B,electron transport layers 124A and 124B, common electrode layers 125Aand 125B, and a sealing layer 126 are sequentially stacked over thefirst auxiliary electrode layer 135W. Further, the planarizing upperlayer 118BY, the planarizing lower layer 118AY and the inorganicinsulating layer 116 are provided therein with a contact hole 116 athatpenetrates from the upper surface of the planarizing upper layer 118BYto the upper surface of the fourth current feeding auxiliary electrodelayer 135Z, and the first auxiliary electrode layer 135W is disposed tobe continuous with an inner peripheral surface of the contact hole 116aand a bottom surface of the contact hole 116 a. In addition, the fourthcurrent feeding auxiliary electrode layer 135Z and the first auxiliaryelectrode layer 135W are in contact with each other at least in apartial area 135Za, in the contact hole 116 a, of the upper surface ofthe fourth current feeding auxiliary electrode layer 135Z. In thisinstance, like in Modifications 3 and 4 described above, the firstauxiliary electrode layer 135W is in contact with the common electrodelayer 125B in partial areas 135 a 1 and 135 a 2 on side surface, and isalso in contact with the partial area 135Za of the fourth currentfeeding auxiliary electrode layer 135Z in the contact hole 116 a.

By this, it is ensured that even in the case where a natural oxide layerof aluminum is formed at a surface layer 201W of the second currentfeeding auxiliary electrode layer 200W on the first auxiliary electrodelayer 135W, the common electrode layer 125 and the fourth currentfeeding auxiliary electrode layer 135Z are electrically connected toeach other through the first auxiliary electrode layer 135W, along theroutes C3 and C4 depicted in FIG. 15A. Therefore, the fourth currentfeeding auxiliary electrode layer 135Z can be made to function as acurrent feeding auxiliary electrode for the common electrode layer 125.

As a result, in the display panel 10Z, the sectional area of theauxiliary electrode can be increased by an amount corresponding to therow-directional section of the fourth current feeding auxiliaryelectrode layer 135Z, and the sheet resistance can be thereby reduced,as compared to the display panel 10W. This is effective as means forrestraining a lowering in light take-out efficiency which might begenerated attendant on an increase in pixel density (an increase inresolution). In addition, the configuration in which the auxiliaryelectrode is provided between the channel protection layer 106 and theinorganic insulating layer 116 in the substrate 100 x ensures that thereis little positional limitation due to the pixel electrodes 119 or thelike on the substrate 100 x, and that the degree of freedom in plan-viewlayout of the fourth current feeding auxiliary electrode layer 135Z isenhanced.

Here, also, the position at which to provide the contact hole 116 aisnot limited to the above-mentioned one; for example, the contact hole116 amay be provided at a position different from that in FIG. 15A.

Note that in Modification 5A, by further modifying Modification 5, aconfiguration may be adopted in which the second auxiliary electrodelayer 200W and the hole injection layer 120B are formed by masking theupper surface of the first auxiliary electrode layer 135W in a filmforming step, whereby it is ensured that the second auxiliary electrodelayer 200W and the hole injection layer 120B are not provided on thefirst auxiliary electrode layer 135W.

FIG. 15B is a sectional view of Modification 5A in which the secondauxiliary electrode layer 200W and the hole injection layer 120B are notprovided on the first auxiliary electrode layer 135W in the displaypanel 10Z. In such a configuration, electron transport layers 124A and124B, common electrode layers 125A and 125B, and a sealing layer 126 aresequentially stacked over the first auxiliary electrode layer 135W. Inthe case where the electron transport layers 124A and 124B are formed byvapor deposition, they are not formed on the inner peripheral surface ofthe contact hole 116 a. Therefore, like in Modification 4A, partialareas 135 a 3 and 135 a 4 of the first auxiliary electrode layer 135Wmake direct contact with the common electrode layer 125B on the innerperipheral surface of the contact hole 116 a, and the area of thepartial areas 135 a 3 and 135 a 4 can be increased, as compared toModification 4 depicted in FIG. 14B.

According to such a configuration, the contact area between the commonelectrode layer 125 and the fourth current feeding auxiliary electrodelayer 135Z can be increased, and the sectional area of a conducting pathto the fourth current feeding auxiliary electrode layer 135Z can beincreased. As a result, connection resistance from the common electrodelayer 125 to the current feeding auxiliary electrode can be reduced.

(6) Modification 6

A configuration may be adopted which is obtained by combining theconfiguration of the display panel 10W according to Modification 4 andthe display panel 10Z according to Modification 5 with each other.

FIG. 16A is a sectional view of the vicinity of a second auxiliaryelectrode layer 200 in a display panel 10YZ according to Modification 6.The display panel 10YZ is characterized in that a third current feedingauxiliary electrode layer 135Y is provided between a planarizing lowerlayer 118AY and a planarizing upper layer 118BY, and, further, a fourthcurrent feeding auxiliary electrode layer 135Z is provided betweenlayers of a plurality of layers constituting a substrate 100 x, forexample, between a channel protection layer 106 and an inorganicinsulating layer 116. Here, also, the position at which to provide thefourth current feeding auxiliary electrode layer 135Z between layers ofthe plurality of layers in the substrate 100 x is not limited to theposition between the channel protection layer 106 and the inorganicinsulating layer 116. A second auxiliary electrode layer 200W, a holeinjection layer 120B, electron transport layers 124A and 124B, commonelectrode layers 125A and 125B, and a sealing layer 126 are sequentiallystacked over the first auxiliary electrode layer 135W, like inModifications 3 and 4.

In addition, the planarizing lower layer 118AY and the inorganicinsulating layer 116 are provided therein with a contact hole 116 athatpenetrates from the upper surface of the planarizing upper layer 118BYto the upper surface of the fourth current feeding auxiliary electrodelayer 135Z, and the third current feeding auxiliary electrode layer 135Yis disposed to be continuous with the inner peripheral surface of thecontact hole 116 aand the bottom surface of the contact hole 116 a.Besides, the third current feeding auxiliary electrode layer 135Y andthe fourth current feeding auxiliary electrode layer 135Z are in contactwith each other at least in a partial area 135Za, in the contact hole116 a, of the upper surface of the fourth current feeding auxiliaryelectrode layer 135Z. Further, the planarizing upper layer 118BY isprovided therein with a contact hole 118BYa that penetrates to the uppersurface of the third current feeding auxiliary electrode layer 135Y, andthe first auxiliary electrode layer 135W is disposed to be continuouswith the inner peripheral surface of the contact hole 118BYa and thebottom surface of the contact hole 118BYa. Besides, the first auxiliaryelectrode layer 135W is in contact with the common electrode layer 125Bin partial areas 135 a 1 and 135 a 2 on side surfaces, and the firstauxiliary electrode layer 135W and the third current feeding auxiliaryelectrode layer 135Y are in contact with each other at least in apartial area 135Ya, in the contact hole 118BYa, of the upper surface ofthe third current feeding auxiliary electrode layer 135Y, like inModifications 3 and 4 described above.

By this, it is ensured that even in the case where a natural oxide layerof aluminum is formed at a surface layer 201W of the second currentfeeding auxiliary electrode layer 200W on the first auxiliary electrodelayer 135W, the common electrode layer 125 and the third current feedingauxiliary electrode layer 135Y and, further, the fourth current feedingauxiliary electrode layer 135Z are electrically connected through thefirst auxiliary electrode layer 135W, along routes C5 and C6 depicted inFIG. 16A. Therefore, the third and fourth current feeding auxiliaryelectrode layers 135Y and 135Z can be made to function as a currentfeeding auxiliary electrode for the common electrode layer 125.Accordingly, sheet resistance can be further reduced, and this iseffective in enhancing resolution. In addition, in a layer between thechannel protection layer 106 and the insulating layer 116, the fourthcurrent feeding auxiliary electrode layer 135Z can be freely laid out ona plan-view basis, in a range in which positional limitation due towiring of the TFT circuit is absent.

Note that in Modification 6A, by further modifying Modification 6, aconfiguration may be adopted in which the second auxiliary electrodelayer 200W and the hole injection layer 120B are not provided on thefirst auxiliary electrode layer 135W.

FIG. 16B is a sectional view of Modification 6A in which the secondauxiliary electrode layer 200W and the hole injection layer 120B are notprovided on the first auxiliary electrode layer 135W in the displaypanel 10YZ. In such a configuration, electron transport layers 124A and124B, common electrode layers 125A and 125B, and a sealing layer 126 aresequentially stacked over the first auxiliary electrode layer 135W. Inthe case where the electron transport layers 124A and 124B are formed byvapor deposition, they are not formed on the inner peripheral surface ofthe contact hole 116 a. Therefore, like in Modifications 4 and 5,partial areas 135 a 3 and 135 a 4 of the first auxiliary electrode layer135W make direct contact with the common electrode layer 125B on theinner peripheral surface of the contact hole 116 a, and the area of thepartial areas 135 a 3 and 135 a 4 can be increased, as compared toModification 4A depicted in FIG. 14B.

According to such a configuration, the contact area between the commonelectrode layer 125 and the first current feeding auxiliary electrodelayer 135W can be increased, the sectional area of the conducting pathto the third current feeding auxiliary electrode layer 135Y and thefourth current feeding auxiliary electrode layer 135Z can be increased,and the connection resistance from the common electrode layer 125 to thecurrent feeding auxiliary electrode can be reduced.

Embodiment 2

<How Embodiment 2 of the Present Disclosure has Been Reached>

However, in the case where a metal such as aluminum, copper and silveris used for the auxiliary electrode layer, there arises a problem thatan oxide film is formed at the surface of the auxiliary electrode layer,and the thus formed oxide film leads to an increase in electricresistance between the auxiliary electrode layer and the commonelectrode layer.

Thus, there is a need for an organic EL display panel, and amanufacturing method suitable for manufacturing the organic EL displaypanel, by which the above-mentioned problem can be solved, that is,electric resistance in electrical connection between a common electrodelayer and an auxiliary electrode layer can be reduced, light emissionefficiency can be enhanced, and variability in luminance can berestrained.

<Outline of Embodiment 2 of the Present Disclosure>

According to Embodiment 2 of the present disclosure, there is providedan organic EL display panel having a plurality of pixel electrodesarranged in a matrix pattern on a substrate, with a light emitting layerdisposed on each of the pixel electrodes, the light emitting layercontaining an organic light emitting material, the organic EL displaypanel including: the substrate; the plurality of pixel electrodesarranged in a matrix pattern over the substrate; a first current feedingauxiliary electrode layer disposed to extend in a column or rowdirection in at least one of gaps between adjacent ones of the pixelelectrodes, over the substrate; a second current feeding auxiliaryelectrode layer disposed to extend in the same direction as the firstcurrent feeding auxiliary electrode layer in a partial area on the firstcurrent feeding auxiliary electrode layer; a plurality of light emittinglayers disposed on the plurality of pixel electrodes; and a commonelectrode layer disposed continuously to cover an upper surfaceexclusive of the partial area of the first current feeding auxiliaryelectrode layer and an upper surface of the second current feedingauxiliary electrode layer, as well as an upper side of the plurality oflight emitting layers, in which the first current feeding auxiliaryelectrode layer contains a first metal as a main constituent, whereasthe second current feeding auxiliary electrode layer contains as a mainconstituent a second metal different from the first metal, and theresistance of a surface layer of the second current feeding auxiliaryelectrode layer is higher than the resistance of a surface layer of thefirst current feeding auxiliary electrode layer.

According to this configuration, the electric resistance in electricalconnection between the common electrode layer and the auxiliaryelectrode layer can be reduced, light emission efficiency can beenhanced, and variability in luminance can be restrained.

Here, a metallic oxide layer may be formed at a surface layer of thesecond current feeding auxiliary electrode layer.

In addition, the sheet resistance of the first current feeding auxiliaryelectrode layer may be higher than the sheet resistance of the secondcurrent feeding auxiliary electrode layer.

Besides, the contact resistance between the first current feedingauxiliary electrode layer and the common electrode layer may be lowerthan the contact resistance between the second current feeding auxiliaryelectrode layer and the common electrode layer.

In addition, the surface area of the first current feeding auxiliaryelectrode layer may be greater than the surface area of the secondcurrent feeding auxiliary electrode layer.

Besides, the first metal may be tungsten or molybdenum, and the secondmetal may be aluminum.

In addition, according to a mode of the present disclosure, there isprovided a method of manufacturing an organic EL display panel having aplurality of pixel electrodes arranged in a matrix pattern on asubstrate, with a light emitting layer disposed on each of the pixelelectrodes, the light emitting layer containing an organic lightemitting material, the method including the steps of: forming theplurality of pixel electrodes arranged in a matrix pattern over thesubstrate by a vapor phase growth method; forming a first currentfeeding auxiliary electrode layer disposed to extend in a column or rowdirection in at least one of gaps between adjacent ones of the pixelelectrodes over the substrate by a vapor phase growth method; forming asecond current feeding auxiliary electrode layer disposed to extend inthe same direction as the first current feeding auxiliary electrodelayer in a partial area on the first current feeding auxiliary electrodelayer by a vapor phase growth method; forming the plurality of lightemitting layers on the plurality of pixel electrodes by a wet filmforming method; and forming a common electrode layer continuously tocover an upper surface, exclusive of the partial area, of the firstcurrent feeding auxiliary electrode layer and an upper surface of thesecond current feeding auxiliary electrode layer as well as an upperside of the plurality of light emitting layers by a sputtering method ora CVD method.

By this method, it is possible to manufacture an organic EL displaypanel such that the electric resistance in electrical connection betweenthe common electrode layer and the auxiliary electrode layer can bereduced, light emission efficiency can be enhanced, and variability inluminance can be restrained.

<Details of Embodiment 2>

1.1 Circuit Configuration of Display Device 1000

A circuit configuration of an organic EL display device according toEmbodiment 2 is the same as that of the display device 1 according toEmbodiment 1 depicted in FIG. 1. Therefore, the description of thecircuit configuration will be omitted.

1.2 Circuit Configuration of Display Panel 3010

A circuit configuration of a display panel 3010 according to Embodiment2 is the same as that of the display panel 10 according to Embodiment 1depicted in FIG. 1. Therefore, the description of the circuitconfiguration will be omitted.

In a display panel 3010 according to the present embodiment, a substrate(TFT substrate) formed with thin film transistors is configured on thelower side in the Z-axis direction, and an organic EL element section isconfigured thereon.

1.4.1 Substrate

(1) Substrate 300 x and Interlayer Insulating Layer 318

For connection with wirings connected to sources 51 of pixelscorresponding to pixel electrodes 319, an interlayer insulating layer318 has contact holes (not illustrated) opened at its parts over thewirings, correspondingly to the pixel electrodes 319.

In the case where an upper limit film thickness of the interlayerinsulating layer 318 is not less than 10 μm, variability in filmthickness at the time of manufacture is enlarged, and it becomesdifficult to control a bottom line width. From the viewpoint of alowering in productivity due to an increase in tact, the upper limitfilm thickness of the interlayer insulating film 318 is desirably notmore than 7 μm. In addition, the film thickness of the interlayerinsulating layer 318 and the bottom line width should be comparable toeach other; when the film thickness of the interlayer insulating layer318 is reduced, particularly, when the lower limit film thickness of theinterlayer insulating layer 318 is not more than 1 μm, it becomesdifficult to obtain a desirable bottom line width due to limitations asto resolution. In the case of a general exposure apparatus for flatpanel displays, the lower limit film thickness of the interlayerinsulating layer 318 is 2 μm. Therefore, the thickness of the interlayerinsulating layer 318 is preferably, for example, 1 to 10 μm, morepreferably 2 to 7

1.4.2 Organic EL Element Section

(1) Auxiliary Pixel Electrode 350 and Pixel Electrode 319

As depicted in FIGS. 18 and 19, the interlayer insulating layer 318located at the upper surface of the substrate 300 x is provided withauxiliary pixel electrodes 350 on a sub-pixel 350 se basis. Further,pixel electrodes 319 are stacked on the auxiliary pixel electrodes 350.

The auxiliary pixel electrode 350 and the pixel electrode 319 are forsupplying carriers to a light emitting layer 323; for example, when theyfunction as anode, they supply holes to the light emitting layer 323. Inaddition, since the display panel 3010 is of the top emission type, thepixel electrode 319 has a light reflecting property. The shapes of theauxiliary pixel electrode 350 and the pixel electrode 319 are arectangular flat plate-like shape. The auxiliary pixel electrode 350 andthe pixel electrode 319 are disposed with a spacing λX1 from theadjacent first auxiliary electrode layer 335 in the row direction. Inaddition, the auxiliary pixel electrode 350 and the pixel electrode 319are disposed with a spacing λX2 from the adjacent auxiliary pixelelectrode 350 and pixel electrode 319 in the row direction. Theinterlayer insulating layer 318 is formed, on the upper side of thecontact hole (not illustrated), with a connection recess (contact hole;not illustrated) for the pixel electrode 319, by recessing a part of thepixel electrode 319 in the direction of the substrate 300 x. At thebottom of the connection recess, the pixel electrode 319 and the wiringconnected to the source 51 of the corresponding pixel are connected toeach other.

With the auxiliary pixel electrodes 350 formed on the interlayerinsulating layer 318, adhesion property (close contact property) isenhanced, whereby penetration of hydrogen into layers below theinterlayer insulating layer 318 can be prevented.

Note that the auxiliary pixel electrodes 350 may not necessarily beformed on the interlayer insulating layer 318.

(2) First Auxiliary Electrode Layer 335 and Second Auxiliary ElectrodeLayer 300

As depicted in FIGS. 18 and 19, the interlayer insulating layer 318located at the upper surface of the substrate 300 x is provided withfirst auxiliary electrode layers 335. As depicted in FIG. 19, the firstauxiliary electrode layer 335 is disposed with a spacing λX1 in the rowdirection from the adjacent pixel electrode 319. In addition, asdepicted in FIG. 19, the first auxiliary electrode layer 335 is disposedwith a spacing W3 in the row direction from a base portion 340 of theadjacent bank 622.

Note that the first auxiliary electrode layer 335 may be in contact withthe base portion 340 of the adjacent bank 622, without the presence ofthe spacing W3 therebetween.

Here, the thickness of the first auxiliary electrode layer 335 is, forexample, 50 nm.

Besides, as depicted in FIGS. 18 and 19, a second auxiliary electrodelayer 400 is stacked on the first auxiliary electrode layer 335. Thewidth W1 in the row direction of the second auxiliary electrode layer400 is smaller than the width W2 in the row direction of the firstauxiliary electrode layer 335. In other words, the surface area of thesecond auxiliary electrode layer 400 is smaller than the surface area ofthe first auxiliary electrode layer 335.

(3) Hole Injection Layer 320

As depicted in FIG. 18, hole injection layers 320 are stacked on thepixel electrodes 319. The hole injection layer 320 has a function oftransporting hole, injected from the pixel electrode 319, into the holetransport layer 321.

The hole injection layer 320 includes a lower layer 320A formed on thepixel electrode 319 and formed from a metallic oxide, and an upper layer320B stacked at least on the lower layer 320A and formed of an organicmatter, in this order from the substrate 300 x side. The lower layers320A provided in the blue sub-pixel, the green sub-pixel and the redsub-pixel are referred to a lower layer 320AB, a lower layer 320AG and alower layer 320AR, respectively. In addition, the upper layers 320Bprovided in the blue sub-pixel, the green sub-pixel and the redsub-pixel are referred to as an upper layer 320BB, an upper layer 320BGand an upper layer 320BR, respectively.

In the present embodiment, the upper layers 320B are provided to extendin a linear shape in the column direction in the gaps 622zR, the gaps622zG and the gaps 522zB, which will be described later. However, aconfiguration may be adopted in which the upper layers 320B are formedonly on the lower layers 320A formed on the pixel electrodes 319, andare provided intermittently in the column direction in the gaps 622 z.

(4) Bank 322

As depicted in FIGS. 18 and 19, banks formed from an insulator areformed such as to cover end edges of the pixel electrodes 319, the holeinjection layers 320, the first auxiliary electrode layers 335 and thesecond auxiliary electrode layers 400. The banks include column banks622Y extending in the column direction and provided in plurality andjuxtaposedly in the row direction, and row banks 322X extending in therow direction and provided in plurality and juxtaposedly in the columndirection. As depicted in FIG. 17, the column banks 622Y are provided inthe state of being along the column direction orthogonal to the rowbanks 322X, and the column banks 622Y and the row banks 322X togetherform a grid pattern (where the row banks 322X and the column banks 622Yare not discriminated from each other, they will hereinafter be referredto as “banks 322”).

The shape of the row bank 322X is a linear shape extending in the rowdirection, and its section obtained by cutting in parallel to the columndirection is a normal-tapered trapezoid tapered upward. The row banks322X are provided in the state of being along the row directionorthogonal to the column direction, in such a manner as to penetrateeach column bank 622Y, and each row bank 322X has an upper surface at aposition below upper surfaces 622Yb of the column banks 622Y. Therefore,openings corresponding to self-luminescence regions 300 a are defined bythe row banks 322X and the column banks 622Y.

The row banks 322X are for controlling flow, in the column direction, ofinks containing organic compounds as materials of the light emittinglayers 323. Therefore, the row banks 322X should have an affinity forthe inks of not less than a predetermined value. By such aconfiguration, variations in ink coating amount from sub-pixel tosub-pixel are restrained. The row banks 322X prevent the pixelelectrodes 319 from being exposed, and the regions where the row banks322X are present do not emit light, and these regions do not contributeto luminance.

The row banks 322X are present on the upper side of column-directionallyouter edges 319 a 1 and 319 a 2 of the pixel electrodes 319.

The row banks 322X prevent electric leaks between themselves and thecommon electrode layer 325, and define outer edges of the light emittingregion 300 a of each sub-pixel 300 se in the column direction.

The shape of the column bank 622Y is a linear shape extending in thecolumn direction, and its section obtained by cutting in parallel to therow direction is a normal-tapered trapezoid tapered upward. The columnbanks 622Y dams up row-directional flow of inks containing organiccompounds as materials of the light emitting layers 323, therebydefining row-directional outer edges of the light emitting layers 323 tobe formed.

The column banks 622Y have row-direction base portions defined by theupper side of row-directional outer edges 319 a 3 and 319 a 4 of thepixel electrodes 319 and row-directional outer edges 400 a 1 and 400 a 2of the first auxiliary electrode layers 335. The column banks 622Yprevent electric leaks between themselves and the common electrode layer325, and define outer edges of the light emitting region 300 a of eachsub-pixel 300 se in the row direction. The column banks 622Y should havea repellency to the inks of not less than a predetermined value.

(5) Hole Transport Layer 321

As depicted in FIG. 18, hole transport layers 321 are stacked on thehole injection layers 320 in the gaps 622zR, 622zG and 622zB. Inaddition, the hole transport layers 321 are stacked (not illustrated)also on the hole injection layers 320 at the row banks 322X. The holetransport layer 321 is in contact with the upper layer 320B of the holeinjection layer 320. The hole transport layer 321 has a function oftransporting holes, injected from the hole injection layer 320, into thelight emitting layer 323. The hole transport layers 321 provided in thegaps 622zR, 622zG and 622zB are referred to as a hole transport layer321R, a hole transport layer 321G and a hole transport layer 321B,respectively.

In the present embodiment, like the upper layers 320B, the holetransport layers 321 are provided in a linear shape such as to extend inthe column direction in the gaps 622 z, which will be described later.However, a configuration may be adopted in which the hole transportlayers 321 are provided intermittently in the column direction in thegaps 622 z.

(6) Light Emitting Layer 323

As depicted in FIG. 18, the light emitting layers 323 are stacked on thehole transport layers 321. The light emitting layer 323 is a layerformed from an organic compound, and has a function of emitting lightthrough recombination of holes and electrons therein. The light emittinglayers 323 are provided in a linear shape such as to extend in thecolumn direction in the gaps 622zR, the gaps 622zG and the gaps 622zBwhich are defined by the column banks 622Y. Light emitting layers 323R,323G and 323B that emit light in respective colors (R, G and B) areformed in the red gaps 622zR corresponding to self-luminescence regions300aR in red sub-pixels 300seR, the green gaps 622zG corresponding toself-luminescence regions 300aG in green sub-pixels 300seG, and the bluegaps 622zB corresponding to self-luminescence regions 300aB in bluesub-pixels 300seB, respectively.

(8) Common electrode Layer 325

As depicted in FIGS. 18 and 19, the common electrode layer 325 is formedon the electron transport layer 324. The common electrode layer 325 isformed over the whole surface of the display panel 3010, and serves as acommon electrode for the light emitting layers 323.

As depicted in FIG. 18, the common electrode layer 325 is formed also inthose regions on the electron transport layer 324 which are located onthe upper side of the pixel electrodes 319. The common electrode layer325 sandwiches the light emitting layer 323 together with the pixelelectrode 319 to form a conducting path, thereby supplying carriers tothe light emitting layer 323; for example, where the common electrodelayer 325 functions as a cathode, it supplies electrons to the lightemitting layer 323.

As depicted in FIGS. 18 and 19, the common electrode layer 325 is formedalso in regions over the first auxiliary electrode layers 335 (exclusiveof the parts on the first auxiliary electrode layers 335 at which thesecond auxiliary electrode layers 400 are formed) and the secondauxiliary electrode layers 400. The common electrode layer 325 is formedsuch as to make direct contact with the first auxiliary electrode layers335 and the second auxiliary electrode layers 400 at lacking parts 336,337, 338 and 339 of the electron transport layer 324.

(9) Sealing Layer 326, Bonding Layer 327, Upper Substrate 330, ColorFilter Layer 328, and Light-shielding Layer 329

The descriptions of the same configurations as those in Embodiment 1will be omitted.

1.5 Method of Manufacturing Display Panel 3010

A method of manufacturing the display panel 3010 will be describedreferring to FIGS. 20A to 24.

(1) Preparation of Substrate 300 x

The substrate 300 x formed with a plurality of TFTs and wiring isprepared. The substrate 300 x can be produced by a known TFT productionmethod (FIG. 20A).

(2) Formation of Interlayer Insulating Layer 318

The aforementioned constituent material (photosensitive resin material)of the interlayer insulating layer 318 is applied as a photoresist insuch a manner as to cover the substrate 300 x, and the surface isplanarized, to form the interlayer insulating layer 318 (FIG. 20B).

After the interlayer insulating layer 318 is formed, a photomaskprovided with predetermined openings is placed thereon, and irradiationwith UV rays from above is conducted to expose the interlayer insulatinglayer 318, thereby transferring the pattern possessed by the photomask(FIG. 20C).

Thereafter, development is performed, to form the interlayer insulatinglayer 318 in which contact holes 318a are patterned (FIG. 20D). Thewiring on the substrate 300 x is exposed at bottom portions of thecontact holes 318 a.

While the interlayer insulating layer 318 is formed by use of a positivetype photoresist in the present embodiment, the interlayer insulatinglayer 318 may be formed by use of a negative type photoresist.

(3) Formation of Auxiliary Pixel Electrode 350 and First AuxiliaryElectrode Layer 335

After the interlayer insulating layer 318 having the contact holes 318aopened therein is formed, the auxiliary pixel electrodes 350 and thefirst auxiliary electrode layers 335 are formed (FIG. 21A).

Formation of the auxiliary pixel electrodes 350 and the first auxiliaryelectrode layers 335 is conducted by forming a metallic film by use of asputtering method or the like, followed by patterning by use of aphotolithographic method and an etching method. In this instance, ametallic film is formed along inner walls of the contact holes 318 a,whereby the connection recesses of the auxiliary pixel electrodes 350are formed.

The auxiliary pixel electrode 350 makes direct contact with the wiringon the substrate 300 x that is exposed at the bottom portion of thecontact hole 318 a, to be in electrical connection with the electrode ofthe TFT.

(4) Formation of Pixel Electrode 319 and Second Auxiliary ElectrodeLayer 400

After the auxiliary pixel electrodes 350 and the first auxiliaryelectrode layers 335 are formed, the pixel electrodes 319 and the secondauxiliary electrode layers 400 are formed respectively on the auxiliarypixel electrodes 350 and the first auxiliary electrode layers 335 (FIG.21A).

Formation of the pixel electrodes 319 and the second auxiliary electrodelayers 400 is conducted by forming a metallic film by use of asputtering method or the like, followed by patterning by use of aphotolithographic method and an etching method.

(5) Formation of Lower Layer 320A of Hole Injection Layer 320

After the pixel electrodes 319 and the second auxiliary electrode layers400 are formed, the lower layers 320A of the hole injection layers 320are formed on the pixel electrodes 319 (FIG. 21B).

The lower layers 320A are formed by forming a film of a metal (forexample, tungsten) by use of a sputtering method or a vapor phase growthmethod such as a vacuum deposition method, followed by baking to oxidizethe metal film, and patterning the oxidized metal film on a pixel basisby use of a photolithographic method and an etching method.

(6) Formation of Bank 322

After the lower layers 320A of the hole injection layers 320 are formed,the banks 322 are formed in such a manner as to cover the lower layers320A (FIG. 21C).

In forming the banks 322, first, the row banks 322X are formed, andthereafter the column banks 622Y are formed in such a manner as to formthe gaps 622 z.

In forming the banks 322, first, a film of a constituent material (forexample, a photosensitive resin material) of the banks 322 is stackedlyformed on the lower layers 320A by use of a spin coating method or thelike. Then, the resin film is patterned to sequentially form the rowbanks 322X and the column banks 622Y. The patterning of the row banks322X and the column banks 622Y is conducted by performing exposure whileutilizing a photomask on the upper side of the resin film, followed by adeveloping step and a baking step (approximately 230° C., approximately60 minutes).

Specifically, in a step of forming the row banks 322X, first, aphotosensitive resin film formed from an organic photosensitive resinmaterial such as acrylic resins, polyimide resins and novolak typephenolic resins is formed, followed by drying to evaporate off thesolvent to a certain extent. Then, a photomask provided withpredetermined openings is placed thereon, and irradiation with UV raysfrom above is conducted to expose the photoresist formed of aphotosensitive resin or the like, whereby a pattern possessed by thephotomask is transferred to the photoresist. Next, the photosensitiveresin is developed, to form an insulating layer in which the row banks322X are patterned. In general, a photoresist called a positive type isused. Of the positive type photoresist, the exposed parts are removed bydevelopment, whereas the parts not exposed to light remain without beingremoved by development.

In a step of forming the column banks 622Y, first, a film of aconstituent material (for example, a photosensitive resin material) ofthe column banks 622Y is stackedly formed by use of a spin coatingmethod or the like. Then, the resin film is patterned to open the gaps622 z, thereby forming the column banks 622Y. The formation of the gaps622 z is conducted by performing exposure while disposing a mask overthe resin film, followed by development. The column banks 622Y extend inthe column direction, and provided juxtaposedly through the gaps 622 zin the row direction.

(7) Formation of Organic Functional Layer

The upper layers 320B of the hole injection layers 320, the holetransport layers 321 and the light emitting layers 323 are sequentiallystackedly formed on the lower layers 320A of the hole injection layers320 formed in the inside of the gaps 622 z defined by the column banks622Y, inclusive of the areas on the row banks 322X (FIGS. 21D and 22A).

In forming the upper layers 320B, inks containing conductive polymermaterials such as PEDOT (a mixture of polythiophene andpolystyrenesulfonic acid) are applied to the inside of the gaps 622 zdefined by the column banks 622Y by use of an ink jet method, followedby evaporating off the solvents, or baking. Thereafter, patterning on apixel basis may be performed by a photolithographic method and anetching method.

In forming the hole transport layers 321, an ink containing aconstituent material is applied to the inside of the gaps 622 z definedby the column banks 622Y by use of a wet process such as an ink jetprocess or a gravure printing process, followed by evaporating off thesolvent, or baking. The method for applying the ink of the holetransport layers 321 to the inside of the gaps 622 z is the same as themethod for the upper layers 320B described above. Alternatively,formation of the hole transport layers 321 is conducted by depositing afilm of a metal (for example, tungsten) by use of a sputtering method,followed by baking to oxidize the metal film. Thereafter, patterning ona pixel basis may be conducted by use of a photolithographic method andan etching method.

In forming the light emitting layers 323, inks containing constituentmaterials are applied to the gaps 622 z defined by the column banks 622Yby use of an ink jet method, followed by baking. Specifically, in thisstep, an ink 323RI, 323GI or 323BI containing a material for the organiclight emitting layers for one of colors R, G and B is applied by an inkjet method to fill the gaps 622 z to be sub-pixel forming regions andthe ink filling the gaps 622 z is dried under a reduced pressure,followed by a baking treatment, to form the light emitting layers 323R,323G or 323B. In this instance, in application of the ink for the lightemitting layers 323, first, a solution for forming the light emittinglayers 323 is applied by use of a droplet jetting apparatus. When theapplication of the ink for forming one of the red light emitting layers,the green light emitting layers and the blue light emitting layers tothe substrate 300 x is finished, an ink of another color is next appliedto the substrate, then an ink of a third color is applied to thesubstrate, and thus the ink applying step is conducted repeatedly, tosequentially apply the inks of the three colors. By this, the red lightemitting layers, the green light emitting layers and the blue lightemitting layers are formed on the substrate 300 x in the manner of beingaligned repeatedly in a horizontal direction of the paper surface of thedrawing. The details of the method for applying the inks for the lightemitting layers 323 to the inside of the gaps 622 z are the same asthose of the method for forming the upper layers 320B described above.

The method for forming the upper layers 320B of the hole injectionlayers 320, the hole transport layers 321 and the light emitting layers323 is not limited to the above-mentioned. Other than the ink jet methodand the gravure printing method, there may also be used such knownmethods as a dispenser method, a nozzle coating method, a spin coatingmethod, intaglio printing, and relief printing, to drop or apply theinks.

(8) Formation of Electron Transport Layer 324

After the light emitting layers 323 are formed, the electron transportlayer 324 is formed over the whole surface of the display panel 3010 bya vacuum deposition method or the like (FIG. 22B). The electrontransport layer 324 is formed also on the second auxiliary electrodelayers 400 and the first auxiliary electrode layers 335 (exclusive ofthose areas on the first auxiliary electrode layers 335 at which thesecond auxiliary electrode layers 400 are formed). In this instance, atend portions of the second auxiliary electrode layers 400 and endportions of the first auxiliary electrode layers 335, lacking (stepping)is intentionally generated in the electron transport layer 323, so thatthe end portions of the second auxiliary electrode layers 400 and theend portions of the first auxiliary electrode layers 335 are exposed atthe lacking parts 336, 337, 338 and 339 (FIG. 19).

(9) Formation of Common Electrode Layer 325

After the electron transport layer 324 is formed, the common electrodelayer 325 is formed in such a manner as to cover the electron transportlayer 324 by a CVD method, a sputtering method or the like (FIG. 22C).The common electrode layer 325 is formed also in those areas on theelectron transport layer 324 which are located over the second auxiliaryelectrode layers 400 and the first auxiliary electrode layers 335(exclusive of those parts on the first auxiliary electrode layers 335 atwhich the second auxiliary electrode layers 400 are formed). In thiscase, the common electrode layer 325 comes around into the lacking parts336, 337, 338 and 339 (FIG. 19) of the electron transport layer 324, tobe formed to make direct contact with the end portions of the secondauxiliary electrode layers 400 and the end portions of the firstauxiliary electrode layers 335 that are exposed at the lacking parts ofthe electron transport layer 324.

(10) Formation of Sealing Layer 326

After the common electrode layer 325 is formed, the sealing layer 326 isformed in such a manner as to cover the common electrode layer 325 (FIG.22D). The sealing layer 326 can be formed by a CVD method, a sputteringmethod or the like.

(11) Formation of Color Filter Substrate 331

A step of manufacturing the color filter substrate 331 will beexemplified below.

The transparent upper substrate 330 is prepared, and a material for thelight-shielding layer 329, which contains a UV-curing resin (e.g.,UV-curing acrylic resin) material as a main constituent with a blackpigment added thereto, is applied to a surface on one side of thetransparent upper substrate 330 (FIG. 23A).

A pattern mask PM provided with predetermined openings is placed on theupper surface of the applied light-shielding layer 329, and irradiationwith UV rays is conducted from above (FIG. 23B).

Thereafter, development is conducted by removing the pattern mask PM anduncured portions of the light-shielding layer 329, and curing isperformed, whereon the light-shielding layers 329 in a rectangularsectional shape are completed (FIG. 23C).

Next, a material 328G for a color filter layer 328 (e.g., 328G), whichcontains a UV-curing resin component as a main constituent, is appliedto the surface of the upper substrate 330 formed with thelight-shielding layers 329 (FIG. 23D), a predetermined pattern mask PMis placed thereon, and irradiation with UV rays is conducted (FIG. 23E).

Thereafter, curing is performed, and development is conducted byremoving the pattern mask PM and uncured portions of the paste 328R,whereon the color filter layers 328G are formed (FIG. 23F).

The steps of FIGS. 23D, 23E and 23F are similarly repeated for each ofcolor filter materials, whereby color filter layers 328R and 328B areformed (FIG. 23G). Note that commercially available color filterproducts may be utilized, instead of using the paste 328R.

In this way, the color filter substrate 331 is formed.

(12) Lamination of Color Filter Substrate 331 and Back Panel

Next, a material for the bonding layer 327, which contains a UV-curingresin such as acrylic resin, silicone resin and epoxy resin as a mainconstituent, is applied to the back panel including the layers rangingfrom the substrate 300 x to the sealing layer 326 (FIG. 24A).

Subsequently, the applied material is irradiated with UV rays, tolaminate the back panel and the color filter substrate 331 in the statein which they are relatively positioned (aligned). In this instance,care should be taken to prevent gas from entering between bothsubstrates. Thereafter, both the substrates are baked to complete thesealing step, whereon the display panel 3010 is completed (FIG. 24B).

1.6 Summary

In the case where a metal such as aluminum, copper and silver is used asa material for the auxiliary electrode layer, an oxide film is formed atthe surface (surface layer) of the auxiliary electrode layer, wherebythe contact resistance between the auxiliary electrode layer and thecommon electrode layer is raised.

In order to solve this problem, the display panel 3010 has the pluralityof pixel electrodes 319 arranged in a matrix pattern on the substrate300 x, and the light emitting layer 323 containing an organic lightemitting material is disposed on each pixel electrode 319. The displaypanel 3010 includes: the substrate 300 x; the plurality of pixelelectrodes 319 arranged in a matrix pattern over the substrate 300 x;the first auxiliary electrode layer 335 disposed over the substrate 300x to extend in the column or row direction in at least one of the gapsbetween the adjacent ones of the pixel electrodes 319; the secondauxiliary electrode layer 400 disposed to extend in the same directionas the first auxiliary electrode layer 335 in a partial region on thefirst auxiliary electrode layer 335; the plurality of light emittinglayers 323 disposed on the plurality of pixel electrodes 319; and thecommon electrode layer 325 disposed continuously to cover the uppersurface exclusive of a partial region of the first auxiliary electrodelayer 335 and the upper surface of the second auxiliary electrode layer400 as well as the upper side of the plurality of light emitting layers323. Here, the first auxiliary electrode layer 335 contains a firstmetal as a main constituent, while the second auxiliary electrode layer400 contains as a main constituent a second metal different from thefirst metal. The resistance of the surface layer of the second auxiliaryelectrode layer 400 is higher than the resistance of the surface layerof the first auxiliary electrode layer 335.

According to this configuration, the common electrode layer 325 makescontact with the first auxiliary electrode layer 335 (exclusive of thepartial region mentioned above), and the first auxiliary electrode layer335 makes contact with the second auxiliary electrode layer 400. Inother words, the common electrode layer 325 makes contact with thesecond auxiliary electrode layer 400 through the first auxiliaryelectrode layer 335. Therefore, even in the case where an oxide film isformed at the surface layer of the second auxiliary electrode layer 400,the electric resistance in electrical connection between the commonelectrode layer and the second auxiliary electrode layer can be reduced,owing to the electrical connection of the layers through the firstauxiliary electrode layer 335. As a result, light emission efficiencycan be enhanced, and irregularities in luminance can be restrained.

Here, in the case where tungsten or molybdenum is used as the materialfor the first auxiliary electrode layer 335, an oxide film is not formedat the surface of the first auxiliary electrode layer 335, since themetal is chemically stable at room temperature.

The contact resistance between the second auxiliary electrode layer 400and the common electrode layer 325 is higher than a first predeterminedvalue, whereas the contact resistance between the first auxiliaryelectrode layer 335 and the common electrode layer 325 is lower than thefirst predetermined value.

In addition, the sheet resistance of the second auxiliary electrodelayer 400 is lower than a second predetermined value, while the sheetresistance of the first auxiliary electrode layer 335 is higher than thesheet resistance of the second auxiliary electrode layer 400, and thesheet resistance of the common electrode layer 325 is higher than thesecond predetermined value.

By putting the common electrode layer 325 and the first auxiliaryelectrode layer 335 (exclusive of those parts on which the secondauxiliary electrode layer 400 is formed) in contact with each other, theresistance can be reduced as compared to the contact resistance betweenthe common electrode layer 325 and the second auxiliary electrode layer400.

Besides, since the sheet resistance of the second auxiliary electrodelayer 400 is lower than the sheet resistance of the first auxiliaryelectrode layer 335, the sheet resistance of the first auxiliaryelectrode layer 335 and the second auxiliary electrode layer 400 as awhole can be reduced, as compared to the case where the first metal (forexample, tungsten) is used for the first auxiliary electrode layer 335and the second auxiliary electrode layer 400 as a whole.

In addition, as depicted in FIG. 19, lacking (stepping) is generated inthe electron transport layer 324 at end portions of the second auxiliaryelectrode layers 400 and end portions of the first auxiliary electrodelayers 335, and the common electrode layer 325 and the first auxiliaryelectrode layer 335 are in direct contact with each other, and thecommon electrode layer 325 and the second auxiliary electrode layer 400are in direct contact with each other, at the lacking parts 336, 337,338 and 339. Therefore, a reduction in resistance can be realized.

1.7 Modifications

While the display panel 3010 according to Embodiment 2 has beendescribed above, a thin film of the electron transport layer 324 may beformed without generation of lacking (stepping) at the lacking parts336, 337, 338 and 339 depicted in FIG. 19.

A configuration may be adopted in which at least part of the lackingparts 336, 337, 338 and 339 depicted in FIG. 19 of the electrontransport layer 324 is not come to be lacking but is thinned to athickness of not more than 1 nm, to form thinned parts (notillustrated). By this configuration, a structure can be realized inwhich although the electron transport layer 324 is not partly lacking,the common electrode layer 325 is electrically connected to the secondauxiliary electrode layer 400 or the first auxiliary electrode layer 335at a lower electric resistance at the thinned parts of the electrontransport layer 324 than at the other parts of the electron transportlayer 324. As a result, the electric resistance in electrical connectionbetween the common electrode layer 325 and the second auxiliaryelectrode layer 400 or between the common electrode layer 325 and thefirst auxiliary electrode layer 335 can be reduced, light emissionefficiency can be enhanced, and irregularities in luminance can berestrained.

Embodiment 3

<How Embodiment 3 of the Present Disclosure has Been Reached>

However, when the auxiliary electrodes are formed in the same layer asthe pixel electrodes, there arises a problem that the areas of the pixelelectrodes on the substrate are reduced, and the pixel aperture ratio islowered. In addition, there is a case where a layer having acomparatively high electric resistance is formed between an auxiliaryelectrode and a common electrode layer depending on the manufacturingstep of an organic EL display panel, and, in that case, there is aproblem that the electric resistance between the auxiliary electrode andthe common electrode is raised.

Thus, there is a need for a solution to the above problems, and for anorganic EL display panel and a manufacturing method suitable formanufacturing the organic EL display panel such that in the case wherean organic layer having a comparatively high electric resistance isformed between an auxiliary electrode and a common electrode layer, theelectric resistance in electrical connection between the commonelectrode layer and the auxiliary electrode can be reduced withoutlowering the pixel aperture ratio.

<Details of Embodiment 3>

1.1 Circuit Configuration of Display Device 2000

A circuit configuration of an organic EL display device according toEmbodiment 3 is the same as that of the display device 1 according toEmbodiment 1 depicted in FIG. 1. Therefore, the description of thecircuit configuration will be omitted.

1.2 Circuit Configuration of Display Panel 4010

A circuit configuration of a display panel 4010 according to Embodiment3 is the same as that of the display panel 10 according to Embodiment 1depicted in FIG. 1. Therefore, the description of the circuitconfiguration will be omitted.

1.1.3 Circuit Configuration of Display Panel 4010

The circuit configuration of the display panel 4010 will be describedreferring to FIG. 25. In the display panel 4010, the pixels 4010 ahaving the circuit configuration are arranged in a matrix pattern asillustrated in FIG. 25, to constitute a display region 4010A.

Gate lines GL-1 to GL-n are led out from the gates G₂ of the pixels 4010a arranged in a matrix pattern, and are connected, at connectionsections 4010 b present outside of the display region 4010A, to externalconnection terminals TMscn-1 to TMscn-n through wiring connectionsections CNscn-1 to CNscn-n, and are connected to scan lines Vscn-1 toVscn-n.

Similarly, source lines S1-1 to SL-m are led out from the sources S₂ ofthe pixels 4010 a arranged in the matrix pattern, and are connected, atthe connection sections 4010 b, to external connection terminals TMdat-1to TMdat-m through wiring connection sections CNdat-1 to CNdat-m, andare connected to data lines Vdat-1 to Vdat-m.

In addition, power supply lines Va of the pixels are integratedlyconnected, at the connection section 4010 b, to an external connectionterminal TMa through a wiring connection section CNa.

Note that in the display device 2000 that performs color display, aplurality of adjacent pixels 4010 a (for example, three pixels 4010 a ofluminescent colors of red (R), green (G) and blue (B)) are made to besub-pixels, which may be combined to constitute one pixel.

1.1.4 Sectional Configuration of Display Panel 4010

The display panel 4010 is a top emission type organic EL display panel,in which a TFT layer is formed on the lower side in the Z-axisdirection, a planarizing layer is formed thereon, and an EL layer isfurther formed thereon. (TFT Layer)

The TFT layer will be described referring to FIG. 26. FIG. 26 depicts anexample of sectional configuration in a YZ plane of the display panel4010.

On a substrate 700, gate electrodes 701 and 702 are formed with aspacing therebetween. A gate insulating layer 703 is formed in such amanner as to cover the surfaces of the gate electrodes 701 and 702 andthe substrate 700.

On the gate insulating layer 703, channel layers 704 and 705 are formedcorrespondingly to the gate electrodes 701 and 702, respectively.Besides, a channel protection layer 706 is formed in such a manner as tocover the surfaces of the channel layers 704 and 705 and the gateinsulating layer 703.

On the channel protection layer 706, a source electrode 707 and a drainelectrode 708 are formed with a spacing therebetween and correspondinglyto the gate electrode 701 and the channel layer 704. Similarly, a sourceelectrode 710 and a drain electrode 709 are formed with a spacingtherebetween and correspondingly to the gate electrode 702 and thechannel layer 705. A passivation layer 712 is formed in such a manner asto cover the surfaces of the source electrodes 707 and 710, the drainelectrodes 708 and 709, and the channel protection layer 706.

The gate insulating layer 703 and the channel protection layer 706 areprovided therein with a contact hole on the upper side of a contactregion 702a of the gate electrode 702, and the drain electrode 708 is incontact with the gate electrode 702 at a bottom of the contact hole.

The channel protection layer 706 is provided therein with a contact holeon the upper side of a contact region 704a of the channel layer 704, andthe source electrode 707 is in contact with the channel layer 704 at abottom of the contact hole. Similarly, the channel protection layer 706is provided therein with a contact hole on the upper side of a contactregion 704b of the channel layer 704, and the drain electrode 708 is incontact with the channel layer 704 at a bottom of the contact hole.

The channel protection layer 706 is provided therein with a contact holeon the upper side of a contact region 705a of the channel layer 705, andthe drain electrode 709 is in contact with the channel layer 705 at abottom of the contact hole. Similarly, the channel protection layer 706is provided therein with a contact hole on the upper side of a contactregion 705b of the channel layer 705, and the source electrode 710 is incontact with the channel layer 705 at a bottom of the contact hole.

In addition, the passivation layer 712 is provided therein with acontact hole on the upper side of a contact region 710 a of the sourceelectrode 710, and a pixel electrode 716 which will be described lateris in contact with the source electrode 710 at a bottom of the contacthole.

Note that the gate electrode 701 corresponds to the gate G₂, the sourceelectrode 707 corresponds to the source S₂, and the drain electrode 708corresponds to the drain D2. Similarly, the gate electrode 702corresponds to the gate G₁, the source electrode 710 corresponds to thesource S1, and the drain electrode 709 corresponds to the drain D₁.

(Planarizing Layer)

A planarizing layer will be described referring to FIGS. 26 and 27. FIG.27 depicts an example of sectional configuration in an XZ plane of thedisplay panel 4010.

A lower interlayer insulating layer 713 is formed on the passivationlayer 712, and auxiliary electrodes 714 are formed on the lowerinterlayer insulating layer 713. In addition, an upper interlayerinsulating layer 715 is formed in such a manner as to cover the surfacesof the auxiliary electrode 714 and the lower interlayer insulating layer713.

As depicted in FIG. 26, the lower interlayer insulating layer 713 andthe upper interlayer insulating layer 715 are provided therein with acontact hole on the upper side of a contact region 710 a of the sourceelectrode 710.

As depicted in FIG. 27, the upper interlayer insulating layer 715 isprovided therein with a contact hole on the upper side of a contactregion 714a of the auxiliary electrode 714, and a common electrode layer719 which will be described later is in contact with the auxiliaryelectrode 714 at a bottom of the contact hole.

The auxiliary electrode 714 is provided to extend in an X-axis directionand a Y-axis direction, while avoiding the contact hole that is providedin the lower interlayer insulating layer 713 and the upper interlayerinsulating layer 715 on the upper side of the contact region 710 a ofthe source electrode 710. Note that the contact regions 714 a of theauxiliary electrodes 714 are provided to extend in the Y-axis direction,every a few pixels (for example, every three pixels) in the X-axisdirection.

(EL Layer)

An EL layer will be described referring to FIG. 26.

On the upper interlayer insulating layer 715, the pixel electrodes 716are provided on the pixel 4010 a basis at parts where the contact holeson the upper side of the contact regions 714 a of the auxiliaryelectrodes 714 are not opened. The pixel electrode 716 is connected tothe source electrode through the contact hole opened in the passivationlayer 712, the lower interlayer insulating layer 713 and the upperinterlayer insulating layer 715 on the upper side of the contact region710 a of the source electrode 710.

On the pixel electrodes 716, banks 717 are formed in such a manner as tocover end edges of the pixel electrodes 716. By the surrounding by thebanks 717, openings each corresponding to each pixel 4010 a are defined.

A light emitting layer 718 is formed in the opening defined by the banks717 on the pixel electrode 716.

The common electrode layer 719 is formed in such a manner as to coverthe light emitting layers 718, the banks 717 and the upper interlayerinsulating layers 715. The common electrode layer 719 is formed in thestate of being continuous over the whole part of the display panel, andis connected to the auxiliary electrodes through the contact holes thatare provided in the upper interlayer insulating layer 715 on the upperside of the contact regions 714 a of the auxiliary electrodes 714.

1.3 Manufacturing Method

A method of manufacturing the display panel 4010 will be describedreferring to FIGS. 28A to 29E.

(1) Formation of Gate Electrodes 701 and 702 and Gate Insulating Layer703

On a surface on the upper side in the Z-axis direction of a substrate700, the gate electrodes 701 and 702 are formed with a spacingtherebetween, as depicted in FIG. 28A, for example. In forming the gateelectrodes 701 and 702, for example, a metallic thin film of MoW isformed on the surface of the substrate 700 by use of a metal sputteringmethod, and a resist pattern is formed thereon by use of aphotolithographic method. Next, wet etching is conducted, followed byremoving the resist pattern. By this, the gate electrodes 701 and 702are formed.

Note that wiring 701a depicted in FIG. 28A corresponds to the gate linesGL-1 to GL-n.

The gate insulating layer 703 is formed in such a manner as to cover thesurfaces of the gate electrodes 701 and 702 and the substrate 700. Theformation of the gate insulating layer 703 is conducted by use of aplasma CVD method or a sputtering method.

(2) Formation of Channel Layers 704 and 705 and Channel Protection Layer706

On a surface of the gate insulating layer 703, the channel layers 704and 705 are formed with a spacing therebetween, as depicted in FIG. 28B,for example. The formation of the channel layers 704 and 705 isconducted, for example, by forming an oxide semiconductor film by use ofa sputtering method, and patterning the film by use of aphotolithographic method and a wet etching method.

The channel protection layer 706 is stackedly formed in such a manner asto cover the surfaces of the channel layers 704 and 705 and the gateinsulating layer 703. The formation of the channel protection layer 706is conducted by stackingly forming a layer of SiO by use of a plasma CVDmethod or a sputtering method, followed by an annealing treatment at atemperature of not lower than the film forming temperature in a dry airor oxygen atmosphere.

(3) Formation of Source Electrodes 707 and 710 and Drain Electrodes 708and 709 and Formation of Passivation Layer 712

On a surface of the channel protection layer 706, the source electrodes707 and 710 and the drain electrodes 708 and 709 are formed, as depictedin FIG. 28C, for example.

First, contact holes are opened in the relevant parts (the parts on theupper side of the contact regions 702 a, 704 a, 704 b, 705 a and 705 bof the gate electrode 702 and the channel layers 704 and 705) of thegate insulating layer 703 and the channel protection layer 706. Theformation of the contact holes is conducted by forming a pattern by useof a photolithographic method, followed by etching by use of a dryetching method. Next, for example, a metallic thin film of Ti, ametallic thin film of Al and a metallic thin film of Ti are sequentiallystacked by use of a sputtering method. Then, the source electrodes 707and 710 and the drain electrodes 708 and 709 are patterned by use of aphotolithographic method and a wet etching method.

Note that wiring 707 a depicted in FIG. 28C corresponds to the sourcelines SL-1 to SL-n. In addition, wiring 709 a depicted in FIG. 28Ccorresponds to the power supply lines Va.

The passivation layer 712 is formed in such a manner as to cover thesource electrodes 707 and 710, the drain electrodes 708 and 709 and thechannel protection layer 706. The formation of the passivation layer 712is conducted by use of a plasma CVD method, an ALD (Atomic LayerDeposition) method or a sputtering method.

(4) Formation of Lower Interlayer Insulating Layer 713, AuxiliaryElectrode 714 and Upper Interlayer Insulating Layer 715

The lower interlayer insulating layer 713 is stackedly formed in such amanner as to cover the passivation layer 712. The formation of the lowerinterlayer insulating layer 713 is conducted by applying theaforementioned organic material, and planarizing the surface thereof.

The auxiliary electrode 714 is formed by forming a metallic film oftungsten (W) by use of a sputtering method or a vacuum deposition methodor the like, followed by patterning the metallic film by use of aphotolithographic method and an etching method. For example, as depictedin FIG. 28D, the auxiliary electrode 714 is patterned in such a manneras to have a region 714H extending in the X-axis direction and a region714V extending in the Y-axis direction, while avoiding the part locatedon the upper side of the contact region 710 a of the source electrode710. The region 714H is provided to extend in the X-axis direction overa plurality of pixels, whereas the region 714V is provided to extend inthe Y-axis direction over a plurality of pixels. A contact region 714aof the auxiliary electrode 714 is provided in the region 714V.

The upper interlayer insulating layer 715 is stackedly formed in such amanner as to cover the lower interlayer insulating layer 713 and theauxiliary electrode 714. The formation of the upper interlayerinsulating layer 715 is conducted by applying the aforementioned organicmaterial, and planarizing the surface thereof.

(5) Formation of Pixel Electrode 716

Contact holes are opened in the lower interlayer insulating film 713 andthe upper interlayer insulating layer 715 on the upper side of thecontact regions 710 a of the source electrodes 710, and the pixelelectrodes 716 are formed.

The formation of the contact holes is conducted by forming a pattern byuse of a photolithographic method, followed by etching by use of a dryetching method. To form the pixel electrodes 716, a thin film oftungsten (W) and a thin film of aluminum (Al) or an aluminum alloy aresequentially stacked to form a metallic film, by use of a sputteringmethod or a vacuum deposition method or the like, after which patterningis conducted, as depicted in FIG. 28E, for example, by use of aphotolithographic method and an etching method. A plurality of pixelelectrodes 716 are patterned in a matrix pattern, whereby the pluralityof pixel electrodes 716 are formed on the upper interlayer insulatinglayer 715, as depicted in FIG. 29A.

Note that the pixel electrode 716 makes contact with the contact regionof the source electrode 710 through the contact hole, to be electricallyconnected to the source electrode 710.

In addition, in the same procedure for opening the contact holes in thelower interlayer insulating layer 713 and the upper interlayerinsulating layer 715 on the upper side of the contact regions 710 a ofthe source electrodes 710, contact holes are opened in the upperinterlayer insulating layer 715 on the upper side of the contact regions714 a of the auxiliary electrodes 714.

(6) Formation of Bank 717

The banks 717 are formed in such a manner as to cover edge portions ofthe pixel electrodes 716. The banks 717 are provided in such a manner asto surround openings each defining each pixel, and to cause the surfacesof the pixel electrodes 716 to be exposed at bottom portions of theopenings.

In forming the banks 717, row banks 717H are formed as depicted in FIG.29B, after which column banks 717V are formed as depicted in FIG. 29C.

In forming the banks 717, first, a film of a constituent material (forexample, a photosensitive resin material) of the banks 717 is stackedlyformed on the pixel electrodes 716 and the upper interlayer insulatinglayer 715 by use of a spin coating method or the like. Then, the resinfilm is patterned to sequentially form the row banks 717H and the columnbanks 717V, thereby forming the openings in which the pixel electrodes716 are exposed. The patterning of the row banks 717H and the columnbanks 717V is conducted by performing exposure by utilizing a photomaskon the upper side of the resin film, followed by a developing step and abaking step.

(7) Formation of Light Emitting Layer 718

The light emitting layers 718 are formed by applying an ink containingthe constituent material to the inside of the openings defined by thebanks 717 by use of an ink jet method, followed by baking. Specifically,in this step, the ink containing a material for the organic lightemitting layer for one of colors R, G and B is placed to fill thoseareas of the openings in which the pixel electrodes 716 are exposed byan ink jet method, then the filling ink is dried under a reducedpressure, and is baked, whereby the light emitting layers 718 are formedas depicted in FIG. 29D. In this instance, in application of the ink forthe light emitting layers 718, first, a solution for forming the lightemitting layers 718 is applied by use of a droplet jetting apparatus.After the application of the ink for forming one of the red lightemitting layers, the green light emitting layers and the blue lightemitting layers is finished, an ink of another color is next applied,and an ink of a third color is then applied, and, thus, the ink applyingoperation is repeated, thereby sequentially applying the inks of thethree colors. By this, the red light emitting layers, the green lightemitting layers and the blue light emitting layers are formed in arepeatedly aligned pattern.

(8) Formation of Common Electrode Layer 719

After the light emitting layers 718 are formed, the common electrodelayer 719 is formed over the whole surface of the display panel 4010 bya CVD method, a sputtering method or the like.

The common electrode layer 719 is formed also on the contact holes wherethe contact regions 714 a of the auxiliary electrodes 714 on the upperinterlayer insulating layer 715 are exposed. The common electrode layer719 makes contact with the contact regions 714 a of the auxiliaryelectrodes 714 through the contact holes, to be electrically connectedto the auxiliary electrodes 714.

1.4 Effect

In the display panel 4010, the auxiliary electrodes 714 are formed in alayer different from that of the pixel electrodes 716. Therefore, areduction in the area of the pixel electrodes 716 can be restrained,with the result that a lowering in pixel aperture ratio can berestrained.

In addition, since the auxiliary electrodes 714 are formed in the layerfor exclusive use, the degree of freedom in wiring of the auxiliaryelectrodes 714 is high. Specifically, the auxiliary electrodes 714 canbe freely patterned on the lower interlayer insulating layer 713, ifonly the patterning conforms to the restriction that the auxiliaryelectrodes 714 should be patterned on the lower interlayer insulatinglayer 713 while avoiding the contact holes for permitting electricalconnection between the pixel electrodes 716 and the source electrodes710. By this, the area of the auxiliary electrodes 714 can be easilyenlarged, and, as a result, a lowering in the resistance of the commonelectrode layer can be realized.

2. Modifications

While the display panel 4010 according to Embodiment 3 has beendescribed above, the present disclosure is not limited to the aboveembodiment, except for essential and characteristic constituent elementsthereof. For instance, modes obtained by subjecting the embodiments tovarious modifications conceived by those skilled in the art and modesrealized by arbitrary combinations of the constituent elements andfunctions in each of the embodiments without departing from the gist ofthe present invention are also embraced in the present disclosure. As anexample of such modes, a modification of the display panel 4010 will bedescribed below.

(1) While the auxiliary electrodes 714 have been formed between thelower interlayer insulating layer 713 and the upper interlayerinsulating layer which constitute the planarizing layer in Embodiment 3,this is not limitative of the position at which to form the auxiliaryelectrodes. The auxiliary electrodes can be formed also in the TFTlayer.

As a display panel according to Modification 1, a display panel in whichauxiliary electrodes are formed in a TFT layer will be described below.Note that the descriptions of the same configurations, constituentelements and manufacturing methods as those in Embodiment 3 will beomitted.

(1-1. Configuration)

The configuration of the display panel according to Modification 1 willbe described referring to FIGS. 30 and 31. FIG. 30 depicts an example ofsectional configuration in a YZ plane of the display panel, and FIG. 31depicts an example of sectional configuration in an XZ plane of thedisplay panel.

As depicted in FIG. 31, on a channel protection layer 706, auxiliaryelectrodes 711 are formed in the state of being spaced from sourceelectrodes 707 and 710 and drain electrodes 708 and 709. In addition, apassivation layer 712 is formed in such a manner as to cover thesurfaces of the source electrodes 707 and 710, the drain electrodes 708and 709, the auxiliary electrodes 711 and the channel protection layer706.

On the passivation layer 712 is formed a lower interlayer insulatinglayer 713. The passivation layer 712 and the lower interlayer insulatinglayer 713 are provided therein with contact holes on the upper side ofcontact regions 711 a of the auxiliary electrodes 711, and a commonelectrode layer 719 is in contact with the auxiliary electrodes 711 atbottoms of the contact holes.

Unlike in Embodiment 3 described above, as depicted in FIGS. 30 and 31,auxiliary electrodes 714 and an upper interlayer insulating layer 715are not formed, but pixel electrodes 716, banks 717 and the commonelectrode layer 719 are formed, on the lower interlayer insulating layer713.

Note that though not illustrated, the auxiliary electrodes 711 areprovided to extend in the X-axis direction and/or the Y-axis directioncontinuously over a plurality of pixels, while avoiding the sourceelectrodes 707 and 710 and the drain electrodes 708 and 709. Note thatcontact regions 711a of the auxiliary electrodes 711 are provided toextend in the Y-axis direction, every a few pixels in the X-axisdirection.

(1-2. Constituent Material)

As the constituent material of the auxiliary electrodes 711, there canbe used the same material as the constituent material of the sourceelectrodes 707 and 710 and the drain electrodes 708 and 709.Specifically, a stacked body of titanium (Ti) and aluminum (Al) (Ti/Al(or Al alloy)/Ti) and a stacked body of copper-manganese (CuMn), copper(Cu) and molybdenum (Mo) can be used.

(1-3. Manufacturing Method)

A method of manufacturing the display panel according to Modification 1will be described.

The auxiliary electrodes 711 are formed on the channel protection layer706. In forming the auxiliary electrodes 711, a metallic thin film ofTi, a metallic thin film of Al and a metallic thin film of Ti aresequentially stacked by use of a sputtering method. Then, the auxiliaryelectrodes 711 are patterned as depicted in FIG. 32 by use of aphotolithographic method and a wet etching method. Note that theformation of the auxiliary electrodes 711 can be performed together withthe formation of the source electrodes 707 and 710 and the drainelectrodes 708 and 709.

The opening of contact holes in the lower interlayer insulating layer713 on the upper side of the contact regions 711 a of the auxiliaryelectrodes 711 can be carried out in Embodiment 3 in the same procedureas that in opening the contact holes in the upper interlayer insulatinglayer 715 on the upper side of the contact regions 714 a of theauxiliary electrodes 714.

(1-4. Effect)

In the display panel 4010 according to Modification 1, the auxiliaryelectrodes 714 are formed in a layer different from that of the pixelelectrodes 716. Therefore, a reduction in the area of the pixelelectrodes 716 can be restrained, with the result that a lowering inpixel aperture ratio can be restrained.

In addition, since the auxiliary electrodes 711 are formed from the sameconstituent material and in the same layer as the source electrodes 707and 710 and the drain electrodes 708 and 709, it is possible to simplifythe manufacturing step.

(2) While the auxiliary electrodes have been formed in the TFT layer andnot formed in the planarizing layer in the display panel according toModification 1, the auxiliary electrodes may be formed in both the TFTlayer and the planarizing layer.

As a display panel according to Modification 2, a display panel in whichauxiliary electrodes are formed in both a TFT layer and a planarizinglayer will be described below. Note that the descriptions of the sameconfigurations, constituent materials and manufacturing methods as thosein Embodiment 3 or Modification 1 will be omitted.

(2-1. Configuration)

The configuration of the display panel according to Modification 2 willbe described referring to FIG. 33.

As depicted in FIG. 33, like in Modification 1, an auxiliary electrode711 is formed on a channel protection layer 706 in the state of beingspaced from source electrodes 707 and 710 and drain electrodes 708 and709.

In addition, like in Embodiment 3, an auxiliary electrode 714 and anupper interlayer insulating layer 715 are formed over a lower interlayerinsulating layer 713.

A passivation layer 712 and the lower interlayer insulating layer 713are provided therein with a contact hole on the upper side of a contactregion 711 a of the auxiliary electrode 711, and the auxiliary electrode714 is in contact with the auxiliary electrode 711 at a bottom of thecontact hole.

(2-2. Manufacturing Method)

A method of manufacturing the display panel according to Modification 2will be described.

Like in Modification 1, the auxiliary electrode 711 is formed on asurface of the channel protection layer 706, after which the contacthole is opened in the lower interlayer insulating layer 713 on the upperside of the contact region 711 a of the auxiliary electrode 711.

After the contact hole is opened in the lower interlayer insulatinglayer 713, the auxiliary electrode 714 is formed. The formation of theauxiliary electrode 714 is conducted by forming a metallic film oftungsten (W) by use of a sputtering method or a vacuum deposition methodor the like, followed by patterning the metallic film as depicted inFIG. 34, for example, by use of a photolithographic method and anetching method. The auxiliary electrode 714 and the auxiliary electrode711 make contact with each other at the bottom of the contact holeopened in the lower interlayer insulating layer 713 on the upper side ofthe contact region 711 a of the auxiliary electrode 711. Besides, acommon electrode layer 719 and the auxiliary electrode 714 make contactwith each other in a contact region 714 a provided in the auxiliaryelectrode 714.

(2-3. Effect)

In the display panel 4010 according to Modification 2, the auxiliaryelectrodes 714 are formed in a layer different from that of pixelelectrodes 716. Therefore, a reduction in the area of the pixelelectrodes 716 can be restrained, with the result that a lowering inpixel aperture ratio can be restrained.

In addition, since the auxiliary electrodes 714 are formed in a layerfor exclusive use, the degree of freedom in layout of the auxiliaryelectrodes 714 is high. This ensures that the area of the auxiliaryelectrodes 714 can be easily enlarged, and, as a result, a lowering inthe resistance of the common electrode layer can be realized.

Besides, since the auxiliary electrodes 711 are formed from the sameconstituent material and in the same layer as the source electrodes 707and 710 and the drain electrodes 708 and 709, it is possible to simplifythe manufacturing step.

(3) In a step of manufacturing an organic EL display panel, forenhancing light emission efficiency, an organic layer such as anelectron transport layer having a function of transferring electrons,injected from a common electrode layer, into a light emitting layer canbe formed between the light emitting layer and the common electrodelayer. When the organic layer is formed on a front surface of thedisplay panel by use of a film forming method such as a vacuumdeposition method after the formation of the light emitting layer, therearises a problem that since the organic layer comparatively high inelectric resistance is formed between the auxiliary electrode and thecommon electrode layer, the electric resistance between the auxiliaryelectrode and the common electrode layer is raised. As a countermeasureagainst this problem, the organic layer may be formed while avoiding acontact part between the auxiliary electrode and the common electrodelayer by use of a mask, whereby the electric resistance between theauxiliary electrode and the common electrode layer can be prevented frombeing raised. In addition, by specially designing the shape of thecontact part between the auxiliary electrode and the common electrodelayer, it is possible to prevent the rising in the electric resistancebetween the auxiliary electrode and the common electrode layer, withoutusing mask vapor deposition.

As a display panel according to Modification 3, a display panel in whichin the case of forming an organic layer such as an electron transportlayer between a light emitting layer and a common electrode layer, arising in the electric resistance between the auxiliary electrode andthe common electrode layer can be prevented without using mask vapordeposition will be described. Note that the descriptions of the sameconfigurations, constituent materials and manufacturing methods as thosein Embodiment 3, Modification 1 or Modification 2 will be omitted.

(3-1. Configuration)

The configuration of the display panel according to Modification 3 willbe described referring to FIG. 35. FIG. 35 depicts an example ofsectional configuration in an XZ plane of the display panel.

In the display panel 4010 according to Modification 3, an electrontransport layer 720 is formed between a light emitting layer 718 and acommon electrode layer 719. The electron transport layer 720 is formedin the state of being continuous over the whole part of the displaypanel 4010. Specifically, the electron transport layer 720 is formedalso over the auxiliary electrode layer 714 exposed at a bottom of acontact hole opened in an upper interlayer insulating layer 715, and thecommon electrode layer 719 is formed further thereover.

A connection part between the auxiliary electrode 714 and the commonelectrode layer 719 in the display panel according to Modification 3will be described referring to FIG. 36. FIG. 36 is a schematic sectionalview of the connection part between the auxiliary electrode 714 and thecommon electrode layer 719 in the display panel according toModification 3, and corresponds to that part of the display panelaccording to Modification 3 which is indicated by symbol 800 in FIG. 35.

As depicted in FIG. 36, a contact hole is opened in part of that portionof a lower interlayer insulating layer 713 which is located on the lowerside of the auxiliary electrode 714, and a passivation layer 712 isexposed at a bottom of the contact hole. In addition, the auxiliaryelectrode 714 is formed with a recess which is recessed toward thepassivation layer 712 side (the substrate 700 side), along the contacthole.

The upper interlayer insulating layer 715 is formed on the upper side ofthe auxiliary electrode 714, and the upper interlayer insulating layer715 is provided therein with a contact hole in which a contact region714 a inclusive of the recess of the auxiliary electrode 714 is exposed.

The electron transport layer 720 is formed over the upper interlayerinsulating layer 715 and over the auxiliary electrode 714 exposed viathe contact hole. The electron transport layer 720 is completely orpartially lacking (between ends 720 a and 720 b, or between ends 720 cand 720 d, in the figure) at the recess of the auxiliary electrode 714,and a contact surface 714 c of the auxiliary electrode 714 is exposed atthe lacking parts.

The common electrode layer 719 is formed over the electron transportlayer 720. The common electrode layer 719 is formed in such a manner asto make direct contact with the contact surface 714 c of the auxiliaryelectrode 714 that is exposed at the lacking part (between the ends 720a and 720 b, or between the ends 720 c and 720 d) of the electrontransport layer 720.

(3-2. Constituent Material)

For the electron transport layer 720, an organic material having a highelectron transporting property is used. Examples of the organic materialto be used for the electron transport layer 720 include 7E electronlow-molecular-weight organic materials such as oxadiazole derivatives(OXD), triazole derivatives (TAZ) and phenanthroline derivatives (BCP,Bphen). In addition, the electron transport layer 720 may include alayer formed from an organic material having a high electrontransporting property doped with a dopant metal selected from amongalkali metals and alkaline earth metals. Besides, the electron transportlayer 720 may include a layer formed from sodium fluoride. The alkalimetals specifically include Li (lithium), Na (sodium), K (potassium), Rb(rubidium), Cs (cesium), and Fr (francium). The alkaline earth metalsspecifically include Ca (calcium), Sr (strontium), Ba (barium) and Ra(radium).

(3-3. Manufacturing Method)

A method of manufacturing the display panel according to Modification 3will be described referring to FIGS. 37A to 37G.

FIGS. 37A to 37G are figures for explaining a method of manufacturing aconnection part of the auxiliary electrode 714 and the common electrodelayer 719 in the display panel according to Modification 3.

First, the lower interlayer insulating layer 713 is formed on thepassivation layer 712 (FIG. 37A), the thus formed lower interlayerinsulating layer 713 is patterned by use of a photolithographic method,and thereafter etching is conducted by use of a dry etching method, toopen a contact hole (FIG. 37B).

After the contact hole is opened in the lower interlayer insulatinglayer 713, a metallic film of tungsten (W) is formed by use of asputtering method or a vacuum deposition method or the like, and themetallic film is patterned by use of a photolithographic method and anetching method, to form an auxiliary electrode 714 (FIG. 37C). In thisinstance, by forming the metallic film along an inner wall of thecontact hole, a recess of the auxiliary electrode 714 is formed.

After the auxiliary electrode 714 is formed, the upper interlayerinsulating layer 715 is formed in such a manner as to cover the lowerinterlayer insulating layer 713 and the auxiliary electrode 714 (FIG.37D), the thus formed upper interlayer insulating layer 715 is patternedby use of a photolithographic method, and thereafter etching isconducted using a dry etching method, to open a contact hole (FIG. 37E).

After the contact hole is opened in the lower interlayer insulatinglayer 713, the electron transport layer 720 is formed by a vacuumdeposition method or the like (FIG. 37F). In this instance, filmformation is conducted in such a manner that lacking (stepping) isintentionally generated at a contact surface 714 c of the recess of theauxiliary electrode 714, so that the contact surface 714 c of the recessof the auxiliary electrode 714 is exposed at the lacking part.

After the electron transport layer 720 is formed, the common electrodelayer 719 is formed in such a manner as to cover the electron transportlayer 720 by a CVD method or a sputtering method or the like (FIG. 37G).In this instance, film formation is conducted in such a manner that thecommon electrode layer 719 comes around into the lacking part of theelectron transport layer 720, to make direct contact with the contactsurface 714 c of the recess of the auxiliary electrode 714 that isexposed at the lacking part of the electron transport layer 720.

(3-4. Configuration in which Auxiliary Electrode 714 and CommonElectrode Layer 719 Make Direct Contact)

Of the auxiliary electrode 714, the inclination angle of the contactsurface 714 c is desirably 60 to 120 degrees. If the inclination angleis less than 60 degrees, the electron transport layer 720 would notundergo cutting (stepping), so that it is difficult to secure electricalconnection of the auxiliary electrode 714 with the common electrodelayer 719. If the inclination angle exceeds 120 degrees, on the otherhand, the common electrode layer 719 would also undergo cutting(stepping) at the inner wall of the recess of the auxiliary electrode714, so that it is difficult to secure contact of the auxiliaryelectrode 714 with the common electrode layer 719. This inclinationangle coincides with the inclination angle of a side surface of thecontact hole opened in the lower interlayer insulating layer 713, and,therefore, can be controlled by light exposure amount at the time offorming the contact hole in the lower interlayer insulating layer 713.The depth of the recess of the auxiliary electrode 714 is set in therange of 1 to 7 μm, for example. The width of the recess of theauxiliary electrode 714 is set in the range of 2 to 10 μm, for example.

By the adoption of such a shape, it is ensured that the electrontransport layer 720 formed on the auxiliary electrode 714 is formed inthe manner of breaking off (undergoing cutting or stepping) at therecess of the auxiliary electrode 714. To be more specific, the electrontransport layer 720 is provided with a spacing between the ends 720 aand 720 b (or between the ends 720 c and 720 d) such that the contactsurface 714 c of the auxiliary electrode 714 is exposed there. On theother hand, the common electrode layer 719 is formed to make contactwith the contact surface 714 c of the auxiliary electrode 714, in themanner of coming around into the space between the ends 720 a and 720 b(or between the ends 720 c and 720 d) of the electron transport layer720.

The auxiliary electrode 714 is desirably formed by a film forming methodexcellent in step coverage property (for example, a sputtering method ora CVD method), in order that the auxiliary electrode 714 will notundergo stepping at the side surface of the contact hole in the lowerinterlayer insulating layer 713. In addition, even where a film formingmethod excellent in step coverage is used, stepping may be generated ifthe film thickness of the auxiliary electrode 714 is excessively small.Therefore, the auxiliary electrode 714 is preferably formed in a filmthickness of not less than 25 nm.

The electron transport layer 720 is desirably formed by a film formingmethod comparatively poor in step coverage (for example, a vacuumdeposition method), in order that the electron transport layer 720 willundergo stepping at the recess of the auxiliary electrode 714 and thecontact surface 714 c will be exposed there. Besides, if the filmthickness of the electron transport layer 720 is excessively small,electrons would migrate directly from the common electrode layer 719into the light emitting layer 718, inhibiting a function of restrictinginjection of electrons into the light emitting layer 718 from beingexhibited. Therefore, the electron transport layer 720 is desirablyformed in a film thickness of not less than 3 nm. On the other hand,thickening of the electron transport layer 720 lowers the transmittanceof the electron transport layer 720, and hampers the generation ofstepping. In order to prevent light transmitted through the electrontransport layer 720 from being excessively attenuated and in order tointentionally generate stepping at the recess of the auxiliary electrode714, the electron transport layer 720 is preferably formed in athickness of not more than 40 nm.

The common electrode layer 719 is desirably formed by a film formingmethod excellent in step coverage (for example, a sputtering method or aCVD method) such that the common electrode layer 719 is formed in themanner of coming around to the stepping part of the electron transportlayer 720. If the common electrode layer 719 is excessively thin,stepping of the common electrode layer 719 may be generated; therefore,the common electrode layer 719 is desirably formed in a film thicknessof not less than 25 nm. On the other hand, thickening of the commonelectrode layer 719 lowers the transmittance of the common electrodelayer 719, and, therefore, the common electrode layer 719 is desirablyformed in a film thickness of not more than 300 nm.

(3-5. Effect)

The display panel according to Modification 3 has a configuration inwhich the auxiliary electrode 714 is provided with the recess, wherebythe electron transport layer 720 is made to undergo stepping, so thatthe contact surface 714 c of the auxiliary electrode 714 exposed due tothe stepping and the common electrode layer 719 make direct contact witheach other. By such a configuration, it is ensured that it isunnecessary, in forming the electron transport layer 720, to performmask vapor deposition for forming the electron transport layer 720 whileavoiding the auxiliary electrode 714; as a result, a lowering inproductivity attendant on high-accuracy aligning of a precision mask canbe obviated.

Note that also in the case of forming auxiliary electrodes in a TFTlayer and a planarizing layer as in the display panel according toModification 2, an effect similar to the above-mentioned can be obtainedby forming the auxiliary electrodes as depicted in FIGS. 38 and 39.

(4) While a configuration in which the electron transport layer 720 islacking such that the contact surface 714 c is exposed at the recess ofthe auxiliary electrode 714 has been adopted in the display panelaccording to Modification 3, the lacking may not be present and thecontact surface 714 c may not be completely exposed, so long as theelectric resistance in electrical connection between the commonelectrode layer 719 and the auxiliary electrode 714 can be reduced. Forexample, a configuration may be adopted in which the electron transportlayer 720 is thinned to a film thickness of, for example, not more than1 nm at its part for contact with the contact surface 714 c in therecess of the auxiliary electrode 714, and the common electrode layer719 is electrically connected to the auxiliary electrode 714 at a lowerelectric resistance at the thinned part of the electron transport layer720 than at the other parts of the electron transport layer 720.(5) In the embodiments described above, a hole injection layer may beformed between the pixel electrode 716 and the light emitting layer 718.

The hole injection layer has a function of assisting generation of holesand injecting and transporting the holes stably to the light emittinglayer 718. The hole injection layer is, for example, a layer formed froman oxide of silver (Ag), molybdenum (Mo), chromium (Cr), vanadium (V),tungsten (W), nickel (Ni), iridium (Ir) or the like, or a layer formedfrom a conductive polymer material such as PEDOT (a mixture ofpolythiophene and polystyrenesulfonic acid).

3. Supplements

The configurations of the present disclosure will be further describedbelow.

-   (1) An organic EL display panel according to a first mode of the    present disclosure includes: a substrate; a thin film semiconductor    layer disposed on the substrate; a lower insulating layer disposed    on the thin film semiconductor layer; a current feeding auxiliary    electrode disposed partly on the lower insulating layer and having a    recess recessed toward the substrate side; an upper insulating layer    disposed over the lower insulating layer and the auxiliary    electrode; and an EL element disposed on the upper insulating layer.    The upper insulating layer is formed therein with a contact hole    which reaches the recess of the auxiliary electrode. The EL element    includes a pixel electrode disposed at a part on the upper    insulating layer where the contact hole is not opened, a light    emitting layer disposed on the pixel electrode, and a common    electrode layer disposed on the light emitting layer and in the    contact hole. In the contact hole, the common electrode layer is    formed along a hole inner wall and a surface of the auxiliary    electrode.-   (2) An organic EL display panel according to a second mode of the    present disclosure is the organic EL display panel according to the    first mode, in which the EL element further includes a functional    layer disposed on the light emitting layer and in the contact hole,    on the lower side of the common electrode layer. In the contact    hole, the functional layer is formed along a hole inner wall and a    surface of the auxiliary electrode, and is lacking or thinned at a    part located at an inner wall of the recess of the auxiliary    electrode, and the common electrode layer is in direct contact with    the auxiliary electrode exposed due to the lacking of the functional    layer or is electrically connected to the auxiliary electrode at a    lower resistance at the thinned part of the functional layer than at    the other parts of the functional layer.-   (3) An organic EL display panel according to a third mode of the    present disclosure is the organic EL display panel according to the    first mode, in which where the auxiliary electrode is defined as a    first auxiliary electrode and the contact hole is defined as a first    contact hole, the thin film semiconductor layer includes a gate    electrode disposed on the substrate, a source electrode and a drain    electrode which are disposed over the gate electrode, and a second    auxiliary electrode which is disposed in the same layer as the    source electrode and the drain electrode and which is disposed at a    part located under the first auxiliary electrode. The lower    insulating layer is formed therein with a second contact hole    reaching the second auxiliary electrode. In the second contact hole,    the first auxiliary electrode is formed along a hole inner wall and    a surface of the second auxiliary electrode.-   (4) A method of manufacturing an organic EL display panel according    to a fourth mode of the present disclosure includes the steps of:    forming a thin film semiconductor layer on a substrate; forming a    lower insulating layer on the thin film semiconductor layer; forming    a current feeding auxiliary electrode partly on the lower insulating    layer, the current feeding auxiliary electrode having a recess    recessed toward the substrate side; forming an upper insulating    layer over the lower insulating layer and the auxiliary electrode;    forming the upper insulating layer with a contact hole which reaches    the recess of the auxiliary electrode; and forming an EL element on    the upper insulating layer. The step of forming the EL element    includes the steps of: forming a pixel electrode at a part on the    upper insulating layer where the contact hole is not formed; forming    a light emitting layer on the pixel electrode; and forming a common    electrode layer on the light emitting layer and in the contact hole.    The step of forming the common electrode layer includes forming the    common electrode layer in the contact hole along a hole inner wall    and a surface of the auxiliary electrode.-   (5) A method of manufacturing an organic EL display panel according    to a fifth mode of the present disclosure is the method of    manufacturing the organic EL display panel according to the fourth    mode, in which the step of forming the EL element includes a step of    further forming a functional layer over the light emitting layer and    in the contact hole, on a lower side of the common electrode layer.    The step of forming the functional layer includes forming the    functional layer in the contact hole along a hole inner wall and a    surface of the auxiliary electrode by a vacuum deposition method in    such a manner that the functional layer is lacking or thinned at a    part located on an inner wall of the recess of the auxiliary    electrode. The step of forming the common electrode layer includes    forming the common electrode layer by a sputtering method or a CVD    method in such a manner that the common electrode layer makes direct    contact with the auxiliary electrode exposed due to lacking of the    functional layer or that the common electrode layer is electrically    connected to the auxiliary electrode at a lower resistance at the    thinned part of the functional layer than at the other parts of the    functional layer.-   (6) A method of manufacturing an organic EL display panel according    to a sixth mode of the present disclosure is the method of    manufacturing the organic EL display panel according to the fourth    mode, in which where the auxiliary electrode is defined as a first    auxiliary electrode and the contact hole is defined as a first    contact hole, the step of forming the thin film semiconductor layer    includes the steps of: forming a gate electrode on a substrate;    forming a source electrode and a drain electrode over the gate    electrode; and forming a second auxiliary electrode in the same    layer as the source electrode and the drain electrode. Further, the    method of manufacturing the organic EL display panel further    includes a step of forming the lower insulating layer with a second    contact hole which reaches the second auxiliary electrode. The step    of forming the first auxiliary electrode includes forming the first    auxiliary electrode in the second contact hole along a hole inner    wall and a surface of the second auxiliary electrode.-   (7) An organic EL display panel according to a seventh mode of the    present disclosure includes: a substrate; a gate electrode disposed    on the substrate; a source electrode and a drain electrode which are    disposed over the gate electrode; a current feeding auxiliary    electrode disposed in the same layer as the source electrode and the    drain electrode; an insulating layer disposed over the source    electrode, the drain electrode and the auxiliary electrode; and an    EL element disposed over the insulating layer. The insulating layer    is formed therein with a contact hole which reaches the auxiliary    electrode. The EL layer includes a pixel electrode disposed at a    part on the insulating layer where the contact hole is not opened, a    light emitting layer disposed on the pixel electrode, and a common    electrode layer disposed on the light emitting layer and in the    contact hole. In the contact hole, the common electrode layer is    formed along a hole inner wall and a surface of the auxiliary    electrode.-   (8) An organic EL display panel according to an eighth mode of the    present disclosure includes: a substrate; a gate electrode disposed    on the substrate; a source electrode and a drain electrode which are    disposed over the gate electrode; a current feeding first auxiliary    electrode disposed in the same layer as the source electrode and the    drain electrode; a lower insulating layer disposed over the source    electrode, the drain electrode and the first auxiliary electrode; a    current feeding second auxiliary electrode disposed at that part on    the lower insulating layer which is located over the first auxiliary    electrode; an upper insulating layer disposed over the lower    insulating layer and the second auxiliary electrode; and an EL    element disposed on the upper insulating layer. The lower insulating    layer is formed therein with a first contact hole which reaches the    first auxiliary electrode. The second auxiliary electrode is formed    in the first contact hole along an inner wall of the first contact    hole and a surface of the first auxiliary electrode. The upper    insulating layer is formed therein with a second contact hole which    reaches the second auxiliary electrode. The EL element includes a    pixel electrode disposed at a part on the upper insulating layer    where the second contact hole is not opened, a light emitting layer    disposed on the pixel electrode, and a common electrode layer    disposed on the light emitting layer and in the second contact hole.    In the second contact hole, the common electrode layer is formed    along a hole inner wall and a surface of the second auxiliary    electrode.    <Summary>

In the organic EL display panel according to Embodiment 3 of the presentdisclosure, the auxiliary electrodes are formed in a layer differentfrom that of the pixel electrodes. Therefore, a reduction in the area ofthe pixel electrodes can be restrained, with the result that a loweringin pixel aperture ratio can be restrained. In addition, since theauxiliary electrodes are formed in a layer for exclusive use, the areaof the auxiliary electrodes can be enlarged and, therefore, a loweringin the resistance of the common electrode layer can be realized.Further, the recess in the surface of the auxiliary electrode ensuresthat even in the case where an organic layer having a comparatively highelectric resistance is formed between the auxiliary electrode and thecommon electrode layer, it is possible, by utilizing film formingmethods different in step coverage as a film forming method for formingthe organic layer and a film forming method for forming the commonelectrode layer, to easily realize a lowering in the resistance inelectrical connection between the auxiliary electrode and the commonelectrode layer.

Although the technology pertaining to the present disclosure has beenfully described by way of examples with reference to the accompanyingdrawings, various changes and modifications will be apparent to thoseskilled in the art. Therefore, unless such changes and modificationsdepart from the scope of the present disclosure, they should beconstrued as being included therein.

What is claimed is:
 1. An EL (Electro Luminescence) display panelcomprising: a substrate; a plurality of pixel electrodes on thesubstrate; a plurality of light emitting layers, wherein each lightemitting layer of the plurality of light emitting layer is on acorresponding pixel electrode of the plurality of pixel electrodes,wherein each of the plurality of light emitting layers comprises a lightemitting material; a first current feeding auxiliary electrode layerextending in a column or row direction in at least one of gaps betweenadjacent pixel electrodes of the plurality of pixel electrodes, whereinthe first current feeding auxiliary electrode layer comprises a metaldifferent from aluminum, and the metal is lower than aluminum in contactresistance in air; a second current feeding auxiliary electrode layersuperposed on the first current feeding auxiliary electrode layer,wherein the second current feeding auxiliary electrode layer comprisesaluminum; and a common electrode layer continuously covering the firstcurrent feeding auxiliary electrode layer and the second current feedingauxiliary electrode layer as well as an upper side of each of theplurality of light emitting layers, wherein the common electrode layercontacts the first current feeding auxiliary electrode layer in apartial area on a wall surface perpendicular to an upper surface of thefirst current feeding auxiliary electrode layer.
 2. The EL display panelaccording to claim 1, wherein an oxide of aluminum is formed at least ata surface layer of the second current feeding auxiliary electrode layer.3. The EL display panel according to claim 1, wherein a functional layercomposed of at least one layer disposed continuously to cover the firstcurrent feeding auxiliary electrode layer and the second current feedingauxiliary electrode layer as well as an upper side of the plurality oflight emitting layers is further provided between the second currentfeeding auxiliary electrode layer and the common electrode layer, thefunctional layer is lacking or thinned in a vicinity of a partial areaof the first current feeding auxiliary electrode layer, and thethickness of the first current feeding auxiliary electrode layer isgreater than the thickness of the functional layer on the light emittinglayer.
 4. The EL display panel according to claim 1, wherein theresistance in a vicinity of a surface layer of the second currentfeeding auxiliary electrode layer is higher than the resistance in avicinity of a surface layer of the first current feeding auxiliaryelectrode layer.
 5. The EL display panel according to claim 1, whereinthe contact resistance between the first current feeding auxiliaryelectrode layer and the common electrode layer is lower than the contactresistance between the second current feeding auxiliary electrode layerand the common electrode layer.
 6. The EL display panel according toclaim 1, wherein the sheet resistance of the material is higher than thesheet resistance of aluminum.
 7. The EL display panel according to claim1, wherein the metal different from aluminum is at least one metalselected from among tungsten, chromium, titanium, molybdenum, nickel,copper, lanthanum, and indium.
 8. The EL display panel according toclaim 1, wherein the first current feeding auxiliary electrode layer iscomposed of ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide).
 9. The ELdisplay panel according to claim 3, wherein when the functional layer isreferred to as a first functional layer, a second functional layerdisposed discontinuously under the plurality of light emitting layersand over the first current feeding auxiliary electrode layer and thesecond current feeding auxiliary electrode layer is further providedbetween the second current feeding auxiliary electrode layer and thefirst functional layer.
 10. The EL display panel according to claim 3,wherein a transparent conductive layer composed of ITO or IZO anddisposed discontinuously under the plurality of light emitting layersand over the first current feeding auxiliary electrode layer and thesecond current feeding auxiliary electrode layer is further providedbetween the second current feeding auxiliary electrode layer and thefunctional layer.
 11. The EL display panel according to claim 1, whereinthe common electrode layer includes a transparent conductive layercomposed of ITO or IZO.
 12. The EL display panel according to claim 1,wherein the common electrode layer includes a metal electrode layercontaining silver as a main constituent.
 13. The EL display panelaccording to claim 1, wherein a planarizing layer composed of aplanarizing lower layer and a planarizing upper layer which contain aresin as a main constituent is provided over the substrate, a thirdcurrent feeding auxiliary electrode layer is disposed to extend in acolumn or row direction between the planarizing lower layer and theplanarizing upper layer, the planarizing upper layer is formed thereinwith a contact hole penetrating to an upper surface of the third currentfeeding auxiliary electrode layer, with the first current feedingauxiliary electrode layer being electrically connected to the thirdcurrent feeding auxiliary electrode layer through the contact hole, thecommon electrode layer is disposed to be continuous with an innerperipheral surface and a bottom surface of the contact hole, and thethird current feeding auxiliary electrode layer and the common electrodelayer are electrically connected to each other through the first currentfeeding auxiliary electrode layer.
 14. The EL display panel according toclaim 13, wherein a functional layer is further disposed between thebottom surface of the contact hole and the common electrode layer in thecontact hole, and the depth of the contact hole is greater than thethickness of the functional layer, and the first current feedingauxiliary electrode layer and the common electrode layer are in contactwith each other at least in a partial area on the inner peripheralsurface of the contact hole in the first current feeding auxiliaryelectrode layer.
 15. The EL display panel according to claim 1, whereinthe substrate includes a TFT (Thin Film Transistor) substrate and aninsulating layer provided over the TFT substrate, the insulating layercontaining a resin as a main constituent, a planarizing layer containinga resin as a main constituent is provided over the substrate, a fourthcurrent feeding auxiliary electrode layer disposed to extend in a columnor row direction is provided between the TFT substrate and theinsulating layer, the planarizing layer is formed therein with a contacthole penetrating from an upper surface of the planarizing layer to alower surface of the fourth current feeding auxiliary electrode layer,with the first current feeding auxiliary electrode layer beingelectrically connected to the fourth current feeding auxiliary electrodelayer through the contact hole, the common electrode layer is disposedto be continuous with an inner peripheral surface and a bottom surfaceof the contact hole, and the fourth current feeding auxiliary electrodelayer and the common electrode layer are electrically connected to eachother through the first current feeding auxiliary electrode layer. 16.The EL display panel according to claim 15, wherein a functional layeris further disposed between a bottom surface of the contact hole in thesubstrate and the common electrode layer in the contact hole, and thedepth of the contact hole is greater than the thickness of thefunctional layer, and the first current feeding auxiliary electrodelayer and the common electrode layer are in contact with each other atleast in a partial area on the inner peripheral surface of the contacthole in the first current feeding auxiliary electrode layer.
 17. The ELdisplay panel according to claim 1, wherein the substrate includes a TFTsubstrate and an insulating layer provided over the TFT substrate, theinsulating layer containing a resin as a main constituent, a planarizinglayer composed of a planarizing lower layer and a planarizing upperlayer which contain a resin as a main constituent is provided over thesubstrate, a third current feeding auxiliary electrode layer disposed toextend in a column or row direction is provided between the planarizinglower layer and the planarizing upper layer, a fourth current feedingauxiliary electrode layer disposed to extend in the column or rowdirection is provided between the TFT substrate and the insulatinglayer, the planarizing lower layer, the planarizing upper layer and theinsulating layer are formed therein with a contact hole which penetratesto an upper surface of the fourth current feeding auxiliary electrodelayer, the first current feeding auxiliary electrode layer iselectrically connected to the third current feeding auxiliary electrodelayer through the contact hole, the third current feeding auxiliaryelectrode layer is electrically connected to the fourth current feedingauxiliary electrode layer through the contact hole, the common electrodelayer is disposed to be continuous with an inner peripheral surface anda bottom surface of the contact hole, and the third current feedingauxiliary electrode layer and the fourth current feeding auxiliaryelectrode layer are electrically connected to the common electrode layerthrough the first current feeding auxiliary electrode layer.
 18. The ELdisplay panel according to claim 17, wherein a functional layer isfurther disposed between a bottom surface of the contact hole and thecommon electrode layer in the contact hole, and the depth of the contacthole is greater than the thickness of the functional layer, and thefirst current feeding auxiliary electrode layer and the common electrodelayer are in contact with each other at least in a partial area on aninner peripheral surface of the contact hole in the first currentfeeding auxiliary electrode layer.
 19. An EL (Electro Luminescence)display panel comprising: a substrate; a plurality of pixel electrodeson the substrate; a plurality of light emitting layers, wherein eachlight emitting layer of the plurality of light emitting layer is on acorresponding pixel electrode of the plurality of pixel electrodes; afirst current feeding auxiliary electrode layer extending in at leastone of gaps between adjacent pixel electrodes of the plurality of pixelelectrodes, wherein the first current feeding auxiliary electrode layercomprises a material different from aluminum; a second current feedingauxiliary electrode layer superposed on the first current feedingauxiliary electrode layer, wherein the second current feeding auxiliaryelectrode layer comprises aluminum; and a common electrode layercontinuously covering the first current feeding auxiliary electrodelayer and the second current feeding auxiliary electrode layer as wellas an upper side of each of the plurality of light emitting layers,wherein the common electrode layer contacts the first current feedingauxiliary electrode layer in a partial area on a wall surfaceperpendicular to an upper surface of the first current feeding auxiliaryelectrode layer.